Top ten best fanbases.
Basis: Hometown crowd reach, defined as the percentage of the metropolitan area that watched, attended, or listened to a game in the last year.
Three years' worth of television ratings.
Three years of stadium attendance based on the percentage of capacity reached.
Three years of merchandise sales, according to NFLShop.com.
Social media reach, using a combination of Facebook and Twitter followers based on the team's metro population
Starting with #1:
#1 Green Bay Packers - In Photos: The NFL's Best Fans - Forbes