Although sports account for just barely 1 percent of all TV programming, it accounts for 7 percent of the total cost of pay-TV, and 50 percent of the of Tweets about television, according to Nielsen's 2013 Year in Sports Media Report. We can go on and on about how sports programming has become central to the business model of live cable TV (and therefore a central driver of the cost of cable), but that's for another day. Today, let's look at TV demographics.

Yes, the NFL is the most-watched sport. But which sport's audience is richest? Whitest? Youngest? Fortunately, Nielsen tracks that data, too. First some highlights, then the graphs. (Note: Nielsen's survey figures are heavy on older, whiter audiences, since they're more likely to own a television and pay for cable.)

The NBA has the youngest audience, with 45 percent of its viewers under 35. It also has the highest share of Black viewers, at 45 percent—three times higher than the NFL or NCAA basketball. Major League Baseball shares the most male-heavy audience, at 70 percent, with the NBA. The NHL audience is the richest of all professional sports. One-third of its viewers make more than $100k, compared to about 19 percent of the general population.

Nascar's audience has the highest share of women (37 percent) and highest share of White people (94 percent). The Professional Golfers Association has the oldest audience by multiple measures: smallest share of teenagers; smallest share of 20- and early 30-somethings; and highest share of 55+ (twice as high, in the oldest demo, as the NBA or Major League Soccer).

Major League Soccer has the highest share of Hispanics by far (34 percent; second is the NBA at 12 percent) and the lowest income of any major sports audience. Nearly 40 percent of its fans make less than $40k. The NCAA demographics for football and basketball are practically identical but they are surprising old (about 40% over 55+) and surprisingly White (about 80%), which clearly has as much to do with who owns a TV rather than who follows the sports.