Subtotal:
48 hours solo - 15 blocks 115XPM
48 hours Ypool- 18 blocks 102XPM -- This is 35% less than it should be
Hence it can be assumed that the pool just stealing 30-40%, and at the original commission of 10% is obtained that the pool itself takes 50% of all coins.
The difference is: 115/102 = 12.7% more solo. It is within normal deviation, 48h is not long enough to make any solid conclusions.