Energizer Bunny demand for “The Book of Mormon” pushed the hit tuner into the No. 1 slot in a post-Labor Day Week 15 (Sept. 3-9) that whittled down sales at nearly every production on the boards.“Mormon” ($1,639,848) surpassed more frequent pole-position occupants “The Lion King” ($1,566,963) and “Wicked” ($1,313,195), the latter of which dropped $387,217 in a frame that typically drains the Rialto of attendees because of back-to-school distractions. All in all, though, the early-September dropoff wasn’t as severe as it’s been in past years, with overall sales down about $2.4 million (or around 12%) to $16.9 million for the 21 shows on the boards. Some in the industry attribute the relative robustness to Broadway Week, the fortnight-long program that aims to drum up sales during fallow frames with two-for-one ticket offers. The initiative helped keep B.O. steady at productions including “Evita” ($1,127,304), “The Phantom of the Opera” ($829,896) “Porgy and Bess” ($610,897) and “Chicago” ($609,315). “Newsies,” was down $150,000 to $808,755, while recent addition “Bring It On” ($416,594), was off 21%. Dips at the two titles seem to make sense, since “Newsies,” “Bring It On” and “Mary Poppins” ($637,053) are among the shows likely to attract the young-skewing auds most liable to stay away from the Main Stem in the first week of school. Overall attendance was down by around 9,000 to 181,598, vs. the 164,570 logged during the same frame last year. The 17 musicals grossed $15,208,370 for 89.9% of the total, with attendance of 158,265 and an average paid admission of $96.09. The four plays grossed $1,717,085 for 10.1% of the Broadway total, with attendance of 23,333 and an average paid admission of $73.59.