Guys..!!!
Thats normal, as much people playing and during more time of playing, you sill get less shares.
Thats correct.
Is exactly the same as a mining pool.
You you are mining alone, you get all the shares and all the block reward is for you.
As more people joins the pool , you get less and less shares and less and less rewards.

This is what is happening. More people playing / mining > less shares/rewards!