A long, hot holiday week saw ratings slump across the board. Only one show, the live episode of NBC's America's Got Talent on Monday, managed to draw more than 10 million viewers -- and even its numbers were down from the show's season's average. The Fourth of July fireworks specials on NBC and CBS were also something of a bust. Macy's 4th of July Fireworks Spectacular led with 8.1 million viewers, down 7 percent from last year, while CBS' Boston Pops Fireworks Spectacular , with 5.5 million viewers fell 18 percent from a year ago. The evening newscasts finished in their usual order, all down slightly from the previous week. NBC Nightly News with Brian Williams remained the leader with 7.8 million viewers. ABC World News with Diane Sawyer followed with 7 million total viewers, while the CBS Evening News with Scott Pelley trailed with 5.7 million viewers. Overall ratings tumbled from the comparable week a year ago. CBS averaged a 3.5 rating and a 6 share, down 9 percent; NBC placed second with a 3.0/6, down 14 percent; ABC came in third with a 2.6/5, down 19 percent; Fox trailed with a 2.1/4, down 2 percent.