178K is the biggest I can find a screenshot proof of: https://pbs.twimg.com/media/Aa7f-uvCMAQF1th.png

Thats on one site out of 8 that share the same cluster/platform, so the net total would have been in the mid 200K's.

edit: props to chartbeat for even being able to track such things, I'm just scaling reads, they're scaling writes.