BANGOR, Maine — After five continuous years of growth, revenues at the Hollywood Casino dropped off for the first time in 2011 as the New England gambling market becomes more competitive, according to a new report.

The declining revenues came before the casino added table games to its lineup in March, but the Bangor casino will face increased competition in Maine starting in June with the opening of the Oxford Casino.

Hollywood Casino’s decline in revenues, down 3.6 percent from 2010 to 2011, mirror declines at other New England casinos such as Foxwoods and Monhegan Sun in Connecticut, which both saw declines of between 1 percent and 2 percent, and Newport Grand in Rhode Island, which saw a decline of 6.2 percent, according to an annual study by the Center for Policy Analysis at the University of Massachusetts Dartmouth.

Mainers make up more than 95 percent of Hollywood Casino’s clientele, according to the report, and contributed about $62.5 million of Hollywood Casino’s total earnings of $65.5 million in 2011. Gamblers from Massachusetts and New Hampshire each made up about 1 percent of Hollywood Casino’s customers and contributed $577,000 to the casino’s earnings in 2011.

While Mainers spent less at the Bangor casino, they spent more while gambling out-of-state, according to the report. Maine residents spent an estimated $34.3 million at Connecticut’s two casinos in 2011, compared to $26.6 million in 2010, according to the report.

In all, gamblers contributed more than $28 million to the Maine general treasury and to the city of Bangor in 2011 because of their gaming and related activities at Hollywood Casino, according to the report.