This summer, for the first time ever, there were more female athletes in the U.S. Olympic delegation than there were male athletes. That caused a ripple of geeky excitement among the sports statistics nerd population. We wondered whether it was a fluke, or whether it was actually a trend we'd see reflected anywhere else.

Well, as it turns out, we didn't have to wait very long, and we didn't have to look very far; in fact, we only had to wait a few weeks, and look to our local high schools. The National Federation of State High School Associations just released its annual Sports Participation Survey, which as it has every year for more than two decades, shows more kids playing sports than the previous year. But there's a twist to the 2011-12 academic year's all-time high of 7,692,520 participants - the gain is attributable to a significant increase among girls' participation (an additional 33,984) that more than made up for a 9,419-participant drop in the boys' figures.

The number of boys participating in high school sports (4,484,987) still leads the number of girls (3,207,533), but the number of girls has been on the rise for 23 years straight. Seven of the top 10 boys' sports registered drops in participation, with 11-player football, outdoor track and field, basketball, wrestling, tennis, golf, and swimming and diving all down from last year. Only three sports in that top 10 (baseball, soccer and cross country) showed increases. The girls' sports grew across the board. If you want the full survey, it's available as a free download from the NFHS website; in fact, NFHS has interactive participation data if you want to compare sports year by year, state by state, whatever.

What interests me is the reason for the fluctuating numbers. Certainly, we have all kinds of possible hooks on which to hang the increased female participation: more great female athletes as role models, an increase in interest in staying fit and healthy, more girls interested in getting into sports in order to chase college athletic scholarships, even an increase in interest in specific sports that are suddenly drawing in girls (lacrosse and wrestling, for example, both made gains among girls last year).

Identifying a compelling reason for the downturn in boys' participation is more of a guessing game, even among those in the sports industry. The suggestions are all over the map - peer pressure (could some boys think it's uncool to show enthusiasm for a school activity?), competing activities (are more boys involved in travel teams or other programs that would conflict with the school athletic schedule?), economics (are more boys seeking part-time jobs during the school year than girls, and is this preventing them from participating?) and competition from other sedentary activities (are TV shows and electronic games marketed more effectively toward adolescent boys than girls?). The hypotheses abound.

What's your theory on the decline? Do you think it's a fluke? Something temporary? Or is it something we need to address?