NEW YORK (CNN/Money) - A record number of fans came out to watch major league baseball last season, and they'll pay for that support with higher ticket prices this season.

As most teams open their season Monday, fans will find the average ticket price up 6.3 percent to $21.17, according to Team Marketing Report, a trade publication that tracks ticket prices. That's the largest increase since a 12.4 percent average increase in average ticket prices in 2000, just before the recession.

The Florida Marlins hiked the average ticket price by 30.7 percent, the largest percentage increase, according to TMR. But that only brought the Marlins' average ticket price to $15.55, well below the league average.

David Samson, president of the Marlins, said that because the team had dumped so many players after its 1997 championship, it was reluctant to raise prices after winning the 2003 World Series. But a year later -- with the team still near the bottom of average ticket prices -- the Marlins decided that a larger hike was justified.

The San Francisco Giants, the Chicago White Sox, the Minnesota Twins and the Chicago Cubs also hiked prices more than 10 percent.

The most expensive average ticket price once again was at Fenway Park, home of the World Champion Boston Red Sox and major league baseball's smallest capacity park. The Red Sox average ticket price is $44.56, up 9.3 percent from 2004.

Even at those prices, the Red Sox have essentially sold out the entire season already. The team's Web site said that only scattered single seats, obstructed view seats or standing room tickets are still available.

Officials from the Red Sox were not immediately available for comment.

The Tampa Bay Devil Rays had the cheapest average ticket price at $13.70, with the Kansas City Royals close behind at $13.71.

TMR also compiles something it calls the Fan Cost Index, which calculates the cost of tickets, parking, food and souvenirs for a family of four. That increased 5.6 percent to $164.43. The Red Sox had the most expensive Fan Cost Index at $276.24, while Kansas City families has the cheapest trip to the ballpark at $119.85.

The jump in the league's average ticket price does not include prices for the Washington Nationals, the relocated team charging nearly double the prices charged by the Montreal Expos in 2004. The Nationals' average ticket price is $21.43, or slightly above league average.

TMR said one of the striking factors in the increase this year is that 17 of the other 29 teams raised prices by 1 percent or more. In a typical year only between six and ten teams raise prices, according to the survey.

Becky Wallace, executive editor of TMR, attributed the higher ticket prices to the improved economy and strong demand for tickets in 2004, as well as the anticipation by a number of clubs of increased interest this year that San Francisco Giants star Barry Bonds could challenge baseball's career home-run mark. Bonds is now injured, though, and may not return this season.

Major League Baseball set an attendance record in 2004 with just over 73 million, an 8.1 percent increase from the previous year.

Major League Baseball spokesman Patrick Courtney pointed out that baseball is still the cheapest of the major team sports. The average ticket price in the National Football League last year was $54.75, according to TMR, while the average NBA ticket was $44.68.

Four teams cut ticket prices, including the San Diego Padres, which set a franchise attendance record in their first year in a new park. Its average ticket price is down 2.7 percent. Several teams with new parks have seen a fall off in demand for tickets after their first year in a new facility.

Washington State University Professor Rodney Fort said that while fans and team owners like to blame player salaries for increased ticket prices, studies show little relation between changes in ticket prices and team payrolls.

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