I guess we could estimate it by looking at the ratio of empty blocks to non-empty blocks produced by F2Pool.
If someone wants to tabulate that data, I'll update my post.
If
you by empty you mean coinbase-only, then in the last 27,027 blocks (basically since jan 1st 2015), f2pool-attributed blocks: 5241, of which coinbase-only: 139
For antpool, this is 4506 / 246. Not sure if that's all the info you'd need, though.
See also: Empty blocks [bitcointalk.org]Awesome! Thanks!!
We can estimate the average effective time it takes to process the blocks, then, as
τ ~= T (N
empty / N
notempty)
~= T (N
empty / (N
total - N
empty))
F2Pool:
~= (10 min) x [139 / (5241 - 139)] = 16.3 seconds
AntPool:
~= (10 min) x [246 / (4506 - 246)] = 34.6 seconds