is there a way for you to tell what % of blocks have been full over the last 3 wks and compare that to prior going back to say Jan 1?
i'd include those in the 900+ and 720-750 kB range as being full.
Yes, though I'd have to wonder what's special about the last 3 weeks? BTC China and Antpool increased their max block size a bit before that. Could also use a different metric for 'full' - e.g. "N% of their apparent maximum".
( Some of the discussion since your post may have made this moot - let me know, I can whip something up regardless )