Why am I getting a blended tax rate of 15%?

Last year I had a total income of $19,176 and got a tax rate of 10%. This year my total income is $38,242 what means that I should get a tax rate of 12% as I checked on the bracket calculator, but Im getting a 15% instead, and I cant see how is that even possible when the brackets jump from 12% to 22%.