From the New York Times:

In a sports world without cable, ESPN, sports-talk radio stations or the 24-hour news cycle, Hank Aaron hit his 715th home run. The only stations that mattered were numbered 2 to 13, and on NBC stations on the night of April 8, 1974, Aaron's home run generated a 22.3 rating and a 36 share, meaning 14.7 million households watched some part of the broadcast. Move ahead 33 years and four months to Barry Bonds' record-breaking home run, which was carried nationally on ESPN2. The game generated a 1.1 rating, with 995,000 households and an average of 1.3 million viewers.

Put another way? 10.75 million people—or, approximately ten times the number of viewers who tuned in to see Barry Bonds' home run—instead spent the evening of Tuesday, August 7th watching America's Got Talent in the hopes of seeing a real accomplishment (i.e. a juggling unicyclist-slash-opera-singer) rather than a record-breaking achievement a mere asterisk in the pages of baseball history.