rating percentile

I'm rated 1218 and my percentile is listed at 59.7%; seems (very) high, expecially since my rating was about the same last week and percentile was about 45%.  also I see the average rating on the site is about 1340 so am I correct that 59.7 is not right?

I suspect it has something to do with the "Facebook Chess" merger. One would expect many of their ratings to be low as that is not a dedicated chess site. Maybe the site stats haven't kept up with these developments. I'm just guessing.

50th percentile reflects the median. It's unclear what they mean by "average" but my bost definitions of average (arithmetic mean, harmonic, geometric) these would be expected to be different numbers. Colloquially its hard to interpret what they mean 1340 to signify.