In 1970, the year Secretariat was born, the average number of starts per runner per year was a healthy 10.22. Forego, born that same year, ran 57 times, including 18 starts in 1973. But even those numbers, remarkable by today's standards, don't put the mighty Forego in the same league with some of the true iron horses in the sport's history. Hall of Famer Stymie started 131 times. In 2009, the average number of starts per horse was down to 6.23, a 39-percent decline over the 1970 numbers. The TDN...