An IRA is a type of account and there are many different types of investments you could put in so an average rate of return(I don't like using interest when there are many investments that involve principal fluctuations and so it isn't quite the same as a bank account) depends a good deal on what type of investment you had. If you were in Internet stocks last year you could have lost 70% with Jacob's Internet Fund or probably 30% or more with some tech funds. Meanwhile, Health Care stocks and funds did great returning 50% or more in some cases so there is a WIDE range of returns. Then there are CDs which could range from 4-7%. I'd highly suggest you read through the 13 Steps:
http://www.fool.com/school/13steps/13steps.htm

And then the all about IRAs:

http://www.fool.com/money/allaboutiras/allaboutiras.htm

Did you know there are 10 different kinds?

My Roth IRA last year had one fund that was up 18% and another that was down 5% and this is the risks of investing so much in stocks as I do. Of course, at 25 I do have many many years for my returns to compound.

JB