Hi,
Recently Nanopool announced that they increased share difficulty by x2.
I`ve made a comparison with ethermine in a 15m time frame and the result is obvious.
On ethermine the number of shares in 15 min are 75 and on nanopool the number of shares in 16m are 28.
Here are the two print-screens with my results.
Ethermine Print screen and here
Nanopool Print Screen