Here is the percentage of total betting handle (customer wagers) represented by each sport in 2016.
Football - 41.63%
Basketball - 30.40%
Baseball - 14.69%
It should be noted that 2016 was a bad year for the sportsbooks when it came to parlays at only winning 4.75% of their total betting handle coming from multiple games on a single ticket. This number has been decreasing drastically in recent years and, based on what I hear from sportsbook staffers, I wouldn’t be surprised to see some kind of changes to parlay and teaser payouts in time for next football season.
The next batch of numbers we'll look at is the percent of the total amount wagered that casinos were able to keep from each sport in 2016. This is specifically how much sportsbook operators in Nevada won from each sport.
Football - 5.39%
Basketball - 4.75%
Baseball - 3.08%
As you can see, the more money taken in by the sportbooks on a particular sport, the more money the sportsbooks win in the end.