games in opening is less than games in that position that were played by others.

here's the link: https://www.chess.com/openings/Ware-Opening-Cologne-Gambit

and no, reloading or deleting the cache doesn't help.

maybe the 0 is talking about your games.

@Shepherd-Slanker no, its talking about all titled chess games.

My guess is the number is correct and the graph is actually just for 1. a4

The number on the players is likely incorrect as well since there aren't that many a4 games in the DB