I hate instagram and FB and all my friends and i'm old and stupid, but, i'm also in web analytics, and comparing mid-January to mid-December doesn't make any sense. I mean, I can't think of one, maybe there's some reason that in mid-december, people might be taking a lot more pictures than at other times of the year. Oh wait, I can think of one. A giant one. The biggest one all year.
Or maybe there were more devices going into new owners' hands in mid-december and THAT drove up usage like crazy. Or maybe people take more pictures when they're not at work, and lots of people have lots of days off in Dec and not in Jan. Or maybe oh forget it you get the point.
Compare this week this year to this week last year in December, then do the same in January, and THEN we can talk. Was the week-to-week change different last year? Otherwise you end up with dumb crap like this. Oh, hey, did you hear that Amazon's revenues are down 48% vs. four weeks ago? THEY"RE DOOOOOMED because I'm an idiot.