Tis the season where millions of Americans take a gamble in starting to fill out their NCAA tournament brackets. Men and women will take out their wallets and throw down some money to enter in a pool with other in the hope they make some easy money in applying their college basketball knowledge. How much money do Americans spend during this time of year? It’s very hard to estimate since 90% of all NCAA tournament gambling is off the books. But lets take a look at some history to guage this sports investing event.

In 1999 there was a report issued by then President Bill Clinton:

National Gambling Impact Study Commission, formed by President Clinton, released a 1999 report citing surveys showing that well over 90 percent of all sports betting nationwide takes place off the books. If accurate, that would push the total wagered on the NCAAs across the country closer to $1 billion.

Fast forward to 2014 where more data can be evaluated yet is still a rough estimate, one sports investing website gave this estimate:

The site Pregame.com estimates that wagering on this year’s March Madness tournament will exceed $12 billion, more money than was riding on the Super Bowl. Of that, $3 billion will be put into office pools of tournament brackets.

Comparing those two estimates, NCAA Tournament betting has exploded 1100% in America. Good luck with your tournament pools this year.

H/T The Fiscal Times and BetFirm.com