I'm glad some other people love them some St. Crispin's Day Speech (and I'm a little shocked that no one has corrected the first guy: "We few, we happy few, we band of brothers. For he today that sheds his blood with me shall be my brother . . . " and so on, and so one, and so awesomely on).
Also, to actually contribute something to the main thrust of the thread:
1) There is a general, year-to-year trend which shows an increase in the number of marathons put on in the United States (although there was a dip from 350 to 340 from 2006 to 2007).
2) The number of marathoners has gone up every year since 2001 (with the exception of '01, which some attribute to the terrorist attacks of September 11th). The number of finishers are as follows:
That's some SERIOUS growth.
3) Marathons today are largely participation events: the average male time in '07 was 4:29:52, and the average female time was 4:59:28. That's pretty darn slow (although the medians would likely be a bit faster, and would be a better statistic to look at). I would be interested to see what average times were in the '70s.
4) The percentage of female marathoners seems to have plateaued at about 40% (it was between 39.1% and 40.0% every year 2003-2007). That's obviously a much higher % than than during the running boom.