Staking Tests with various balances: 100/200/500/1000/2000/5000 -
Update after two monthsTime elapsed: ~
56 days / 8 Weeks (snapshot taken at 12.3.18 19:36 GMT) (started on 15th Jan 2018 at 23:42)
The wallet was running almost 24/7 with only some minor downtime of a few hours. (Every address had the same downtime, as they run in the same wallet.)
100 -> 107.5 = 05 staking rewards -> 7.50 %
200 -> 210.5 = 07 staking rewards -> 5.25 %
500 -> 527.2 = 18 staking rewards -> 5.44 %
1000 -> 1059.0 = 40 staking rewards -> 5.90 %
2000 -> 2119.5 = 79 staking rewards -> 5.97 %
5000 -> 5304.1 = 201 staking rewards -> 6.08 %
percentage on the end of the lines above stands for the total interest for the 56 days.
the smallest address still does stand out a bit, but it already got a bit balanced to the other addresses.
This will probably continue to align further.
Current result of all addresses:
Average Interest per day:
0.11%Estimated Interest rate per year for staking 24/7:
47.8% 
Next report in approx. 4 weeks for the quarter results.