Update:

There have been 11700 transactions since block 894289 that have had OP_RETURN size > 83. This is way more than the 30 from the first 4 months and it's probably because of @oomahq

's challenge to make the non-standard OP_RETURNs more than 50% of the total OP_RETURNs.

Running the numbers on these, here are the fee rates that they paid compared to the median fee rate.

On average the 11700 transactions paid 191% more than the median fee rates of the blocks in which they were included. Or put another way, these transactions paid a bit less than triple the median fee rate.

1336 paid less than the median fee rate

2197 paid between the median and 50% more than the median fee rate

3516 paid between 1.5x-2.5x the median fee rate

1554 paid between 2.5x-3.5x the median fee rate

3094 paid more than the 3.5x the median fee rate

1064 were mined by F2Pool

10636 were mined by MARA Pool