I think you are right about the fact that the number don't add up.

50 BTC discovered 699 blocks. So 699*25= 17475 BTC.
In total of those 699 blocks they had 5.897.971.136 shares submitted. I did this times the average pay out per share for that period.

5.897.971.136*0,00000160 = 9445BTC So doing 17475-9445 = 8030BTC in profit.

Ok my apologies for making this topic. It seems like the reported shares in the statistics of 50BTC are way to low. Compared to the calculations that are made somewhere ells.