“The Perks of Being a Wallflower” has been growing quietly for more than a month, becoming one of the best examples this year of an aggressive platform strategy.With five consecutive weekend-over-weekend improvements, the feature adaptation of Stephen Chbosky’s popular 1999 book benefited from having in its corner one of the most sought after moviegoing demos — teens. Summit’s box office success story should yield a tidy profit. “Perks” cost in the low teens, but Summit was able to reduce exposure to less than $5 million thanks to output and foreign licensing deals totaling $8 million-$9 million (or roughly 70% of the pic’s budget). Marketing expenses totaled an additional $10 million-$12 million. Domestic cume is $9.6 million, with just north of $4 million internationally via local distributors. “Perks” has earned the most overseas in the U.K., with $2.8 million. The film’s Stateside B.O. should top out at around $15 million — boosted by steadily growing interest from adults. This past weekend, the film earned $2.153 million from 745 locations vs. the previous weekend’s $2.15 million take from 726. “Perks” centers on a troubled teen, played by Logan Lerman, who befriends a group of outcasts, including characters played by Emma Watson and Ezra Miller. The book, which helmer Chbosky also adapted for the screen, developed cult status among teen readers and stirred up controversy for its depiction of teen sexuality and drug use. John Malkovich produced the film along with Lianne Halfon and Russell Smith. Summit first launched “Perks” on Sept. 21 at four locations in New York and L.A. The distrib expanded the film aggressively the following weekend to 102 engagements and then more than doubled the count to 221 during the pic’s third frame. Entering its sixth week in the U.S., Summit adds just 10 locations today to the pic’s total count.