What 2011’s popcorn fare has lacked in originality, it sure has made up for in coin: This year is poised to deliver the biggest summer box office of all time, only reinforcing Hollywood’s growing obsession with reboots, franchises and sequels.

For the first time ever, the top five pics of summer were all sequels, each crossing the $200 million mark to power the Stateside B.O. to $4.24 billion as of Wednesday. In all likelihood, the Labor Day weekend will boost that total just enough to surpass the $4.34 billion summertime record set in 2009.

Domestically, summertime admissions are up about 2% vs. last year.

Booming international markets were just as bountiful, grossing an eye-popping $8.2 billion this summer, according to studio estimates, to easily surpass last year’s World Cup-depressed $5.8 billion. And the global audience cooked up another first for year as three summer pics hit $1 billion in worldwide grosses — all of them sequels, of course.

Leading the pack worldwide is Warner Bros.’ “Harry Potter and the Deathly Hallows: Part 2,” which has grossed $1.3 billion, followed by Paramount’s “Transformers: Dark of the Moon” with $1.1 billion and Disney’s “Pirates of the Caribbean: On Stranger Tides” with $1.03 billion.

Top three were joined by “The Hangover Part II” and “Fast Five,” if you include the latter pic with its April 29 opening; summer B.O. is historically counted from the first weekend in May. (For calendar sticklers, “Cars 2” would round out the domestic B.O.’s top five summer players.)

What’s more, even some of the summer’s best-performing pics, like “Thor” and “The Smurfs,” kick started franchises of their own.

Overall, 27 films on the 2011 calendar are derived from a previous film, up from a high of 24 in 2003. The summer frame was so thick with nonoriginal properties that only six of the 20 highest-grossing summer pics were not based on previous works.

In both 2010 and 2009, multiple original films figured in the top 10; this year, only “Bridesmaids” did at No. 8.

None of the higher-profile original titles cashed in the way “Inception” did last year. Other than “Bridesmaids,” Par’s “Super 8” reps the best of summer’s fresh fare — and that pic’s $126 million domestic cume falls drastically short of “Inception’s” $271 million. U’s “Cowboys and Aliens” drew relatively few fans, with Stateside totals shy of $100 million.

Few surprises

With four multibillion-dollar franchises — “Pirates of the Caribbean,” “Harry Potter,” “Transformers” and “X-Men” — unspooling their latest installments, a number of records fell this summer.

“On Stranger Tides” first set the overseas debut record, bowing to $260.4 million, only to be trumped nearly two months later by “Deathly Hallows: Part 2.” Harry Potter not only beat Jack Sparrow internationally with a bow of $313.5 million but broke nearly every other opening benchmark worldwide, plus the three-day Stateside debut mark at $169.2 million. “Part 2,” with $482.7 million, beat “Dark of the Moon” ($400.5 million) for the global opening-weekend crown.

B.O. pundits expected pics like “Potter,” “Pirates” and “Transformers” to buoy summer totals. But a few franchise entries turned out to be unexpected summer hits, including Universal’s “Fast Five” and 20th Century Fox’s pair, “X-Men: First Class” and “Rise of the Planet of the Apes.”

“Apes,” which has cumed $150 million domestically, surpassed “First Class” ($146 million) in the U.S. That’s a considerable surprise since both films garnered positive word of mouth and “X-Men,” a fresh take on the property, played during the heat of summer.

“Fast Five” also moved the summer sesh a week earlier, seeing good results before Par launched “Thor” on May 6. “Five,” in 2D only, grossed $209 million domestically, while 3D “Thor” tallied $181 million.

3D stalls, Imax soars

The “Fast Five” vs. “Thor” battle also became a heated scramble for Imax screens, a significant factor this summer. After “Fast Five” bowed in Imax on April 29, the film lost most of its oversized screens to “Thor” the following weekend, partly causing the considerable 62% soph-sesh drop.

While Imax heated up, 3D cooled considerably, dropping steadily from the prior weeks, when “Rio” and “Thor” had 3D returns in the 58%-60% range, to late summer, when major titles plateaued in the 40%-45% range. Some 3D pics without Imax (i.e., “Kung Fu Panda 2”) saw lower takes from the format overall, while for others, like “On Stranger Tides,” Imax boosted what would have been a much-more dismal 3D share had the film not been backed by the largescreen exhib. (“Pirates” grossed 42% from 3D, but of that, Imax contributed 9%; “Panda 2” earned 45% from 3D.)

Imax prexy Greg Foster said fanboy titles in particular can benefit from Imax berths.

According to Foster, the Imax brand also helped boost totals in smaller markets. For example, the Warren theater in Wichita, Kan., ranked 44th in the nation the weekend “Thor” opened, but when “Captain America” — a non-Imax pic — debuted, the theater was 441st overall.

Heated R-rated season

Universal’s “Bridesmaids” was the summer’s biggest sleeper, surprising with $168 million domestically. That beats family pic “Panda 2,” which totaled $164 million without ratings restrictions.

“With ‘Bridesmaids,’ we decided that it was important to be the first of the summer R-rated comedies,” said Nikki Rocco, prexy of domestic distribution for U.

Other R-rated comedies, including “Hangover Part II” and “Horrible Bosses,” outperformed gentler pics at Stateside plexes. “Hangover,” having grossed $254 million, beat “Pirates,” with $240 million; while “Horrible Bosses,” at $114 million, ultimately should outpace “Green Lantern’s” $116 million domestic cume.

Like franchise and comicbook pics, the season’s eight R-rated comedies — more than in any other summer since 1984, when PG-13 ratings were introduced — mostly avoided cannibalizing one another at the box office.

Sony’s “Bad Teacher” crossed the $200 million worldwide mark, with domestic grosses nearing $100 million.

Not every R-rated comedy resonated with auds: Sony stalled with “Friends With Benefits” and “30 Minutes or Less,” as did Universal with “The Change-Up.” Though the Weinstein Co.’s “Our Idiot Brother” was also an R-rated comedy, the modestly budgeted Sundance pickup was affected by Hurricane Irene last weekend. Instead, Disney-DreamWorks’ “The Help” topped the domestic B.O. for the second weekend in a row, ending the summer on a positive note with more than $100 million.

Despite the record summer sesh, year-to-date domestic B.O. was still down 3% overall.