Tax refund vanished when filing unemployment?

I was employed through may of last year before losing my job and spending the rest of the year on unemployment. I was just filing my taxes online and after filing my earned income with my job I was going to be getting roughly $2,000 for a return. But after I filed my unemployment, I now OWE $200. I know all about the fact that I can opt to have taxes taken out of my unemployment checks and that it's taxable income blah blah blah.......I don't need a lesson on how unemployment works (so don't bore me with the details) I'm just wondering how there can be that big of a jump ($2,200) and what is the normal rate of taxes the IRS expects to get out of my unemployment when I file? Is it a percentage or a certain number at different levels like moving into a higher/lower tax bracket?