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(CNN) -- It may not be an "Age of Extinction," but Hollywood is far from happy with the summer box office.

Where are all the blockbusters? Summer is supposed to be Tinseltown's version of the Christmas shopping season, but "Transformers: Age of Extinction" was the first movie of the year to record a $100 million three-day opening weekend, and overall, the box office is down nearly 20% compared with last year.

CNN's complete summer entertainment guide

That comparison is one reason studio executives are reaching for the antacids. Paul Dergarabedian, senior media analyst at Rentrak, cautions that 2013 is a hard act to follow.

"When you have a film kicking off the summer of 2013 like 'Iron Man 3' with $174.1 million, and this year we kick off the summer with 'The Amazing Spider-Man 2' with $91.6 million, that's a pretty big discrepancy," Dergarabedian noted.

"Iron Man 3" wound up grossing $409 million at the domestic box office last year, with "Despicable Me 2" adding $368 million.

In all, seven films topped the $200 million mark last summer. This summer has seen just three: "X-Men: Days of Future Past," "Maleficent" and "The Amazing Spider-Man 2."

Of course, some things are beyond Hollywood's control, like the calendar. "Having the Fourth of July actually land on a Friday didn't help things: When you have people outside watching fireworks on the second-biggest moviegoing day of the week, that's not good for business," Dergarabedian said.

The holiday weekend also featured the latest example of a disturbing trend: the second-weekend slump. Historically, most films don't drop much more than 50% in their sophomore frames, but "Transformers: Age of Extinction" fell more than 60%. So did "X-Men: Days of Future Past," "The Amazing Spider-Man 2" and "Godzilla." That's led to a revolving door of No. 1 movies: "Transformers" is the first film of the year to spend more than one weekend as box office champ since "Captain America: The Winter Soldier" in April.

2013 did have a few high-profile, big-budget flops, observes Dergarabedian. Hollywood hasn't suffered through an "After Earth" or a "Lone Ranger" this year. But plenty of 2014 films have failed to meet expectations, such as the well-reviewed Tom Cruise action flick "Edge of Tomorrow."

"It's over $300 million worldwide, so Tom Cruise is still a movie star worldwide, but in North America, even Tom Cruise couldn't get a number one debut," as "Edge" fell to the teen weeper "The Fault in Our Stars," Dergarabedian recalled.

"How To Train Your Dragon 2" has also failed to soar as high as expected, despite not much competition for family audiences. Indeed, Dergarabedian says that lack of competition may have reduced the demand for "Dragon."

"Moviegoing begets more moviegoing, right? So if you have more product out there, it gets people enthused, it gets families enthused about going out to the movie theater, and when you don't have a lot of family films there, it kind of slows that momentum down," he explained.

And there's not much relief on the horizon: "Dawn of the Planet of the Apes" figures to take over the top spot from "Transformers" this weekend, and Dergarabedian sees "The Purge: Anarchy" and "Guardians of the Galaxy" as other summer bright spots, but none of them figures to help Hollywood dig out of this hole.

In fact, the summer movies that have everyone talking are next summer's expected hits: The "Fantastic Four" reboot, "Batman v. Superman," "Fast & Furious 7" and "Jurassic World," with "Star Wars: Episode VII" following in December, have studio execs wishing the calendar read 2015 already. But Dergarabedian hasn't given up on this summer just yet.

"If you put a big movie into the marketplace, market it well, get that buzz going, you can have big box office," he said. "This could all turn around almost overnight. All we need is two or three movies to perform well beyond expectations, and it could turn this around."

Your move, Hollywood.

Madison Conklin, special to CNN, contributed to this report.