If I and made more this year than I did last year, why am I only getting 4 extra dollars on my federal tax return this year?

In 2015, I received 1,201 back for federal. Block one om W2 was 21,785.

In 2016, I received 1,211 for federal. Block one on W2 was 24,704.21 

And for 2017, it says I will receive 1,215. Block one on W2 is 27,781.51.

I am not well versed in taxes in general, but the return seems a but off this year.