How high is the risk of cancer from CT scans?

I’ve had numerous CT scans in my 20 years of life. In fact, I’ve had 3 in 2012 alone. They have proved to be very beneficial in finding and treating my various health problems. But since I am a cancer survivor (which alone increases my risk of future cancers), I am afraid of the amount of radiation I’m being exposed to. So I am just wondering how high the risk of cancer actually is.