When my younger son was having some medical problems, I had the opportunity to chat with his pediatric urologist while we were waiting for some test results. He told me that circumcision on infants had definitely fallen off over the past couple of decades, but he believed the overall rate had only dropped a little bit: Parents were bringing their kids in at ages up to 6 years at a much higher frequency than when he started his practice. He bemoaned that he hadn't been keeping good statistics from the beginning.
After he'd noticed the change, however, he did start keeping stats. The most significant thing he'd found was that class (clarified to location) seemed to be the biggest determining factor. Boys from middle class and upper-middle class neighborhoods were circumcised, either as infants or as young children, at something like 90%. Boys from lower-class neighborhoods were only 40%, with one significant exception: black infants were circumcised at almost the same rate (the 90% rate) regardless of location. Since he practices in the DFW area, this more or less meant that Hispanics were the ones with the lower rates.
I asked him if he would consider putting checkboxes on his form regarding the reason parents sought circumcision:
[ ] Medical
[ ] Religious
[ ] Cultural
[ ] Asthetics
He said he'd think about it, but was afraid he'd run afoul of professional ethics standards if he did so. I wanted him to explain that, but about then the tests came back, and our chance to talk was over. (My son was fine, by the way.)