If you thought it was getting more expensive to go the movies, your hunch was right. The average ticket price at theaters in the U.S. and Canada last year rose to an all-time high of $7.89, up 5 percent from $7.50 in 2009, according to the National Association of Theatre Owners.

The figure represents a national average of theaters in big cities and small towns alike, and includes discount matinees and children’s prices.

Association spokesman Patrick Corcoran attributed the increase primarily to the growth in 3-D screenings, which can add $2.50 to $4 to the ticket price.

Hollywood is expected to release about 35 3-D films this year, and theater owners are moving rapidly to accelerate the number of 3-D screens to handle the growing pipeline.

Just this week, Regal Entertainment, the nation’s largest theater operator, announced that it would double its number of RealD 3-D screens.

All of which means ticket prices are likely to continue to rise. One AMC location in New York raised eyebrows last summer by selling $20 tickets for Imax 3-D screenings of the DreamWorks Animation movie “Shrek Forever After.”

The price increase came in a year when box office was virtually flat from a year earlier, reaching $10.6 billion in revenue, while attendance dropped 5.3 percent from 2009.

Still, Corcoran downplayed the effect of ticket inflation on attendance, noting that the increase in 2010 was “not way out of line” with average increases over the last five years and was still below what it was in 1970 when factoring in inflation. Then, the average ticket cost $1.55, or $8.71 when adjusted for inflation.

Corcoran attributed the rise in ticket prices to studios releasing fewer movies and fewer hits in the latter part of the year.

“People aren’t staying away because of ticket prices,” Corcoran said, “they are staying away because of the movies.”