Less than 1% because as Andrew Soltis said in "The Inner Game of Chess" that "Chess isn't 99% Tactics, it's 99% Calculation!"
Explain why chess isn't 99% tactics!

A few quotes that may be helpful
"Tactics are the servants of strategy." --Mikhail Botvinnik
"Tactics tend to flow from a positionally superior game."--Bobby Fischer
"In general I consider that in chess everything rests on tactics. If one thinks of strategy as a block of marble, then tactics are the chisel with which a master operates, in creating works of chess art." - Tigran Petrosian
"The tactician must know what to do whenever something needs doing;the strategist must know what to do when nothing needs doing." - Savielly Tartakower
"It is better to follow out a plan consistently even if it isn't the best one than to play without a plan at all. The worst thing is to wander about aimlessly." - Alexander Kotov
"It is not a move, even the best move that you must seek, but a realizable plan." - Eugene Znosko-Borovsky
"Tactics involve calculations that can tax the human brain, but when you boil them down, they are actually the simplest part of chess and are almost trivial compared to strategy." - Garry Kasparov

@AdorableMogwai
Pony up for a diamond membership and you can tackle Silman's 300 lesson "Roots of positional understanding". It's certainly made my misunderstanding more profound.
@chessman1504
What a great collection of quotes! Thanks.

That is really true, the calculation part is paramount. I think it depends on the game. There are some games that are hard hitting tactical blows back to back. Conversely, there are some games that will build up after 100+ moves and win because of the positional understanding of the person.
Is there another way to practice positional understanding aside from the diamond membership?
NICE QUOTES!! :)

That depends on the person and time control.
For some people it is probably 99% tactics.
For me it is 50% tactics and 50% trying to save myself from brilliant ideas gone wrong (and perhaps also from blunders in time pressure).
Idea (one of my not-so-brilliant ones):
For Ivanchuk it is 100% losing on time.

When players who are master or better play you will not often see tactics early.
A tactic is often the end result of positional play with those players.
You build up your position using positional play and at some point there will almost always be a tactic to end the game.

The 99% refers to any players starting point: if you don't start w/ a tactics book you will lose 99% of your games until you read a tactics book--> IMobviouslyHO!

hmm, very interesting. For me, would say my games are about 80% tactics. I spend a long time in each game looking for tactical shots that will win me the game.

Strategy is how you go about stopping your enemy's expected plan and your own plan on how you are gonna bring warfare to the enemy's King. Thus you need to delay the enemy until your situation is good enough to tackle whatever obstacles you expect.
Tactics are the things you do to stop or delay the enemy and help your cause of bringing about the best outcome from each move and th game overall; usually we want Mate but sometimes a draw is the best possible chance.
How tactics do this is via two methods, you use your 'bits' = pieces and pawns to either steal material 'bits' of the enemy or to create a situation that is favourable to your cause. This means killing them enemy so they cannot prevent you from ultimately getting to their King or whatever your shorter term strategy might be such as trapping the enemy Queen; whatever.
So you learn and play open games (eg. 1.e4) that make seeing tactical combinations far easier within an actual game while practicing tactics in a pure form via puzzles so you learn the patterns of pieces which hopefully helps you see those patterns within an actual game where you get no hint of some amazing move to win material or position.
Once you are 'good' at tactics and open games oyu can move onto closed games (eg. d4) where the 'bits' tend to stay on the board and "clutter" the situation, thus making tactical combinations 'harder' to see.
So while there are a ton of things a chess player needs to know about its all meaningless unless the player understands how to carry out their plans using tactics. Thus tactics are your guns for killing or controlling the enemy as well as protecting your troops and King, without tactics we would all just shuffle around the board aimlessly until something 'happened' and that would involve some tactic you are supposed to be able to recognise; hopefully BEFORE it really happens within your game.

I think 'tactics' make up 90% of a new players chess 'needs', the other 10% are pure "Rules" and how the 'bits' move etc. like setting up the board. Over time this percentage drops as a player gets better till at a Master level 'tactics' are less than 20% due to so many other things they "need" to know.
The catch is that, tactics for a beginner while 90% of their needs they can afford an error rate of 90%, thus a player progresses by lowering their error rate from tactics. So a beginner' makes a few moves and then loses material or position from missing tactics, however a Master cannot afford to miss more than 5%; this is a "human-error" factor i estimate.
Remember that if you make a Blunder it is not gauranteed your enemy will both see it and be able to exploit it thus everyone is allowed a few percentages of tactical errors since they are not always game changers. This fact is proven by the fact modern computers do not 'miss' tactical combinations like humans can, thus your chess job is to lower your tactical error rate down toward 5% so you have time to start learning all those other wonderful things a chess Master 'needs' to know...
Accoridng to Merriam Webster the definition of TACTICS is the science and art of disposing and maneuvering forces in combat. As this definition covers any chess move it would seem incorrect, under the technical definition, to claim anything less than 100% of chess moves are tactical in nature.

People who think chess is about 99% tactics are the same people who lose in under 20 moves...
I agree but how do I get out of the rut

I agree but how do I get out of the rut
Simple. Dont try to attack until ALL your pieces are developed.
(There are exceptions of course, but they're rare.)

Accoridng to Merriam Webster the definition of TACTICS is the science and art of disposing and maneuvering forces in combat. As this definition covers any chess move it would seem incorrect, under the technical definition, to claim anything less than 100% of chess moves are tactical in nature.
I've never been very keen on "argument by dictionary". In any case, the terms "tactics" and "strategy" have quite well-defined and distinct meanings in the context of chess. So the thread title injunction probably does have some validity.
Yes, you are of course, quite right... I strongly suspect that I am once again starting to slip into overuse of reductio ad absurdum arguments to grasp at random contrarian positions in an futile effort to distract myself, ever so briefly, from an insipid funding proposal that hides, incompete and uncared for, under this chess.com forum window...
I am not sure of the percentage, but I am pretty sure chess is NOT 99% tactics. What percentage do you think it is and why?
-Bankoscarpa