Here is the NFL Victory Trend Index from Pro Football Prospectus 2008 through Week 9 (data includes games since the 17-week format began in 1990, excluding the 18-week 1993 season):

Through nine games, 1.5 percent of the teams were 9-0; 4.6 percent were 8-1; 11.4 percent were 7-2; 12.8 percent were 6-3; 19.1 percent 5-4; 18.2 percent were 4-5; 16.2 percent were 3-6; 9.7 percent were 2-7; 4.8 percent were 1-8; and 1.2 percent were 0-9.

Teams that started 9-0 finished the season averaging 13.8 wins; 8-1 averaged 12.9 wins; 7-2 averaged 11.3 wins; 6-3 averaged 10.0 wins; 5-4 averaged 8.9 wins; 4-5 averaged 7.0 wins; 3-6 averaged 6.1 wins; 2-7 averaged 4.6 wins; 1-8 averaged 3.1 wins; and 0-9 averaged 1.7 percent.

Teams starting the season 9-0 and 8-1 made the playoffs every time; 7-2 made the playoffs 91.5 percent of the time; 6-3 made the playoffs 74.2 percent of the time; 5-4 made the playoffs 54.5 percent of the time; 4-5 made the playoffs 10.6 percent of the time; 3-6 made the playoffs 3.6 percent of the time; no teams starting 2-7, 1-8 or 0-9 made the playoffs.