How com my car insurance rates goes up instead of down?

first of all i am 21 years old, I NEVER had any kind of accident or ticket or anything like that, I have been driving for about 4 years now.
I used to pay 67.34 $ a month which isnt that bad but now i got a new car and my insurance rates went up to 83 $ a month.
why??
btw i called them and the lady said it has nothing to do with the new car.
but still why did my rates go up if i never had any kind of accident or anything?