Fantasy football leagues: Who's counting?

They’ve been around since the 80s, but fantasy sports have recently exploded – thanks, largely, to football.

The industry has become so large -- $70 billion by some estimates --  that it has its own lobbyists: the Fantasy Sports Trade Association. The interest group's website gives us an intriguing glimpse at the industry, its customers, and its future ties to television.

The FSTA says the average age of a player is 37. He (yes, 66 percent of players are men) likely has a college degree (57 percent have one), and spends an average of $465 per year on fantasy sports.

Right now, the FSTA estimates 56.8 million people play fantasy sports. That number has doubled in just five years. And it's likely to double again. Why? Keep reading.

Fantasy sports started in 1980 with a fantasy baseball game, but football is now the sport of choice. 73 percent of players choose pigskin.

We assumed most players played fantasy sports on their smartphone. We were wrong. Only 37 pecent use a mobile device, according to the FSTA. So, are the rest playing on that desktop computer at work? Probably.

We won’t tell. But the IT department probably already knows, FYI.

The most telling statistic we found is the one that helps explain the avalanche of TV ads for FanDuel and DraftKings (the biggest fantasy sports providers). The FSTA's data reveals that 61 percent of players are watching more live sports on TV. Yes, more TV -- at a time when more people are watching less TV. That is a potential goldmine for advertisers -- and for fantasy sports.