Good answers so far, and I agree with the premise that falls are likely in MTB riding, but consequences can be more severe in road crashes.
But...it depends on how risk-seeking your MTB adventures are. Being older and supposedly wiser now, I try to keep my tires in contact with the ground as much as I can. I used to launch myself regularly because it was so fun. You never quite knew how the landing would be.
My wife would kill me now (talk about severe consequences) if she discovered that I was flying off humps, bumps and ramps when trail riding. She asks me how my rides are, and my safest response is "uneventful".