The legalized U.S. sports betting market doubled in 2021, with more than $52.7 billion wagered throughout the year, according to data intelligence agency Morning Consult.

The spike is the result of legal sports bets launching in 11 states and billions of dollars spent on marketing by gambling operators looking to attract new customers. 12% of adults placed bets once a week, up from 5% in January 2021. 14% of sports bettors said their average bet is more than $100.

Oddsmakers only pocketed approximately $4 billion of the total amount wagered last year.

Currently, 30 states and Washington, D.C., have legalized sports betting, and more young people are participating — 19% of adults aged 21-34 have bet on sports at least once a week, including legal and offshore sportsbooks.