PORTLAND, Ore. (TheStreet) -- As of Sunday's Hall of Fame Game between the Miami Dolphins and Dallas Cowboys, the National Football League is officially back.OK, so it's preseason and little more than a bunch of on-field auditions for hopefuls and finger-crossing by fans who'll just be happy if their team's key players make it to the regular season without suffering some gruesome, season-ending injury. Still, that means the NFL's money machine is cranking again and that it's ready to toy with fans' hearts and finances for yet another season. Last year alone, the NFL produced $9.5 billion in revenue. That's $2 billion more than the $7.5 billion produced by Major League Baseball over the same span and more than the revenue produced by the NCAA ($5.3 billion) and NASCAR ($4.1 billion) combined. Its television revenue is slated to rise from an average of $4 billion a year to $5 billion annually as new contracts kick in. The networks are more than happy to pay after 31 of the 32 most-watched television shows in the fall of 2012 were NFL games. So why should fans expect a fair measure of misery in 2013? Because even $10 billion isn't enough for the sprawling league. Game attendance jumped from a post-recession low of 17.14 million in 2010 to 17.3 million last year, but was still well short of the record 17.6 million that came out in 2006 and 2007. There were nearly 1 million empty seats at regular season games in 2012, up 50% from just four years earlier. Meanwhile ticket revenue has stagnated from increases of 7.2% annually from 2004 through 2008 to just 2.1% from 2008 through 2012, according to Team Marketing Report. Even as the Minnesota Vikings and San Francisco 49ers build stadiums, franchises in smaller markets struggle just to get people into their buildings.