Snapshots from the last two days during which I had 500 SP delegated:

Yesterday earned 0.255 Steem. Over 365 days, that works out to 18.6% ROI.

The day before, 0.302 Steem that works out to 22.05% ROI. Also got 0.004 SBD that day.

Edited to add: And today’s payout of 0.297 works out to 21.67% ROI.