Americans will bet more than $4 billion on the upcoming Super Bowl 50 between the Denver Broncos and the Carolina Panthers, according to the American Gaming Association (AGA). The bad news: only a fraction of those bets will be placed legally.

Of the estimated $.2 billion in bets that will be placed on February 7, nearly 97 percent—or about $4.1 billion worth—will be wagered with internationally regulated sportsbooks, the casino industry trade group said in a statement. That number was a lot higher compared to last year, when Americans bet $3.8 billion with internationally regulated sportsbooks on the Super Bowl matchup between the Seattle Seahawks and the New England Patriots.

The AGA said the illegal marketplace is about 35 times more lucrative than the legal forms of sports betting, such as those offered in Las Vegas.

“As Americans celebrate a milestone Super Bowl, they’ll also bet a record amount on the Big Game,” said AGA President and CEO Geoff Freeman said in a statement. “Just like football, sports betting has never been more popular than it is today. The casino gaming industry is the leading conversation around a new approach to sports betting that enhances consumer protections, strengthens the integrity of games and recognizes fans’ desire for greater engagement with sports.”