The study, published online first in JAMA on 1/26/12, was performed on a representative national sample of Americans as part of the National Health and Nutrition Examination Survey (NHANES). In the study of over 5000 participants, researchers found that both high- and low- risk forms of HPV were quite common in the US population. HPV infection risk increased with age until the early 60s, with two peaks in 30-34 and 60-54 year olds, and other independent risk factors for HPV included being male as opposed to female, being sexually active, having more sex partners, and smoking. Interestingly, neither race nor education level was associated with oral HPV risk, although both are associated with STD risk more generally. This may be because common safe sex precautions are ineffective at preventing oral HPV infection.
On which note, it's worth making a point of the fact that oral HPV infections were associated with sexual activity whether or not the participants had practiced oral sex. Although there may be some reporting bias involved, this strongly suggests that oral HPV can also be transmitted through other sexual activities, such as deep kissing.