NEW YORK — More than two out of three people worldwide tuned in for the Beijing Olympics. Nielsen Media Research says 4.7 billion viewers globally saw at least some of the 17 days of TV coverage last month. This audience was one-fifth larger than the 3.9 billion who watched the 2004 Olympic Games in Athens. Host nation China claimed more viewers than any other nation, Nielsen said Friday, logging an audience reach of 94 percent among its population of 1.3 billion. In the U.S., where NBC and several sister networks aired extensive coverage, the 2008 Olympics took the record as the most-viewed event in American television history.