The final hour of NBC-TV's Saturday broadcast of the Preakness Stakes at Pimlico Racecourse in Baltimore registered a Nielsen rating of 6.8, up 23.6 percent compared to the rating for the final hour of last year's Preakness, according to NBC.\nShare for the final hour was a 16, up 23 percent compared to share of 13 last year. Share measures the percentage of televisions in use that are tuned to the broadcast. \nNBC said that 10.9 million viewers watched the final hour, when the filly Rachel Alexandra beat the gelding Mine That Bird, the Derby winner. Last year, according to NBC, 7.9 million people watched the final hour of the broadcast. \nThe rating this year was the highest since 2004, when Smarty Jones won the Preakness. Rating was a 7.7 that year, and share was a 19. NBC said the rating this year was also the second-highest since 1990, when the rating was a 7.9.\nThe final rating for the entire broadcast will be available Thursday.