http://beta.musicbrainz.org/statistics/timeline/count.ipi suggests so; researching further now.

http://beta.musicbrainz.org/statistics/timeline/count.rating#g-1337947986475.9429/1339786373992.1978/153887.39946380697/184450.40214477212 seems to suggest something similar happened with ratings, http://beta.musicbrainz.org/statistics/timeline/count.rating.raw with raw ratings; this seems to suggest it's some problem with adding together fetch() calls in Data::Statistics.

count.tag.raw is also affected, by the same thing. Subtraction, oddly, seems to work fine.

This works fine on my machine; someone with access to production will need to look at it.

In review at http://codereview.musicbrainz.org/r/2001/