Studios aren’t necessarily calling home about their mid-summer box office report card, but with a few solid A grades so far, nobody is closing the books on what still could be a profitable season at the multiplexes.Year-to-date domestic B.O. receipts are up 4% over last year, but summer totals have slipped 7.5% through the Fourth of July weekend. Some B.O. observers attribute the so-so feel to several factors: n The calendar: Mid-summer is measured from the first Friday of May through July 4. This year, that was nine weeks compared to 10 weeks last year. n No breakout originals: The biggest hits so far have been sequels and remakes such as “Iron Man 2″ and “The Karate Kid.” According to one studio honcho, “We haven’t had a movie that came out of nowhere. And that’s usually the thing that gives the summer a jolt, some sleeper that ends up doing a lot of business.” n It’s (still) 3D crunch time: After the first quarter’s 3D logjam, the format still has little room to breathe with several recent 3D titles impacting each other’s playtime. In comparison with last year’s record-breaking summer, the first nine weeks this year show mid-summer B.O. up 6%. This approach is nice, but a little skewed, since it does not include last year’s Fourth of July weekend (week 10 for 2009). Still, the mid-summer season ended on a high last week, up 18%, as femme auds surprised no one with a massive appetite for Summit’s latest “Twilight” offering “Eclipse.” The film took $176.4 million in its first six days of release, with the June 30 opening day reaching a boffo $68.5 million, a record debut for a Wednesday. Meanwhile, Paramount’s 3D anime adaptation “The Last Airbender” overperformed with five-day totals of $69.3 million. Both films highlight a season lacking in breakout originals. A list of sequels, which were expected to perform well, have topped the summer barrage as of June 7: “Toy Story 3″ ($313.1 million), “Iron Man 2″ ($308.7 million), “Shrek Forever After” ($233.1 million) and “Eclipse.” Last year’s mid-summer period was revived by “The Hangover,” Warner Bros.’ surprise hit, which earned $209 million during the comparable period to date, a particularly unusual feat for an R-rated comedy. And while Paramount’s “Transformers: Revenge of the Fallen” topped last year’s mid-season period, with $299.8 million, Disney/Pixar’s 3D “Up” and “The Hangover” both landed among the top five performers. This summer’s top fresh fare “Grown Ups” has earned a solid $91.7 million for Sony, but nothing out of the ordinary for an Adam Sandler vehicle. Sony’s other standout title “The Karate Kid” overperformed during its opening weekend ($55.7 million) and has since become one of the summer’s surprise hits, with a boffo $157.5 million. The studio was hoping there was still audience awareness from the original “Kid” and that turned out to be the case. The original entries, “Get Him to the Greek” and “Knight and Day,” started out with lackluster results but have cruised to OK takes so far. Universal’s “Greek,” which debuted June 4 with $17.6 million, has reached $58.5 million; “Knight” stands at $52.6 million for 20th Century Fox after a moderate $27.4 million five-day rollout, starting Wednesday, June 18. But in its second outing, “Knight” gained some positive traction among adult audiences, a considerable feat given that new entries “Eclipse” and “Airbender” also played strongly with older auds. Still, original titles aren’t the only films that started out soft. Memorial Day Weekend entries “Sex and the City 2″ and “Prince of Persia: The Sands of Time” disappointed domestically, but overseas totals have helped offset hefty pricetags. In the U.S., both films have yet to cross the $100 million benchmark, while worldwide figures for Warner’s “Sex 2″ stand at $273.6 million and a princely $322.1 million for Disney’s “Prince.” Like “Sex 2″ and “Prince,” profits for U’s Ridley Scott-directed “Robin Hood” were buoyed by international turnouts, reaching $305.8 million worldwide, with more than 65% from foreign auds. The studio’s prexy of domestic distribution Nikki Rocco says that this year’s summer slate points to an increasingly global view in Hollywood. “We tried to do something smart with ‘Robin Hood’ and get out early,” Rocco says, referring to the film’s head start overseas because of the World Cup soccer tournament. “For this film, it wasn’t just about North America, it was about the global number.” The 3D logjam continues to vex distribs and exhibs, even after the first-quarter clutter. Par’s “Shrek” kicked off the summer in 3D and maintained a clear playing field until Disney rolled out “Toy 3″ five weeks later. The squeeze on 3D screens has taken its toll on each new 3D title. “Toy 3″ earned 60% of its opening take from 3D-equipped screens, down from “Shrek’s” 62%. “Airbender” was even lower when it bowed July 1, with 54%. Both “Shrek” and “Toy 3″ maintained a relatively steady hold on 3D profits in holdover frames until additional titles entered the market. With “Airbender” just two weeks into its theatrical run, Universal and Chris Meledandri’s Illumination Entertainment launched toon “Despicable Me” on July 9, further clogging the 3D pipeline. Universal will hope to impress auds with its first in-house toon, as “Despicable Me” looks to buck the slipping 3D portion of the B.O. “Despicable Me” is one of several notable originals that could break the sequel trend this summer. Warner’s highly anticipated “Inception,” which launches July 16 from helmer Christopher Nolan, may be the biz’s best bet. Sony has a pair of fresh offerings, led by Angelina Jolie starrer “Salt,” set for release on July 23, and “The Other Guys,” starring Mark Wahlberg and Will Ferrell, on Aug. 6. Debuting in the U.S. on July 30, Paramount-DreamWorks’ “Dinner for Schmucks” could bank on its comedy mainstays Paul Rudd and Steve Carell, whose first-quarter success “Date Night” has cumed a resilient $97.8 million. Lionsgate’s re-teaming of action heroes in “The Expendables,” with Sylvester Stallone, Jet Li, Jason Statham and Bruce Willis, will roll out on Aug. 13.