Perhaps it's a sign of the growing number of big-screen HDTV sets that have been installed in households throughout the country, but Macy's annual 4th of July Fireworks Spectacular on NBC drew its biggest audience in 11 years Sunday night. The telecast averaged 8.65 million viewers, peaking in the second half-hour with 10.37 million. A repeat at 10 00 p.m. averaged 5.34 million viewers more. CBS did all right with the fireworks, too. Its annual Boston Pops Fireworks Spectacular averaged 6.57 million viewers in the 10 00 p.m. time period. ABC, which has winning Monday nights with The Bachelorette , finished a distant third with 3.09 million viewers for a rerun of the show.