If that's 990 out of 30,000, then that is only 3% of participants. I'd say that you're talking about a motivated group of runners there, too - you're not signing up for a 10mi race unless you've been doing some training. I am going to guess that in reality, if you took a sample of all runners, you're looking at less than 1% total and if you grabbed a random cross-section of society, you're looking at closer to 0.01%. The vast majority of Americans couldn't finish a mile even at an easy jogging pace and forget about a 7 minute pace, much less doing that for 10 miles.