X-Men Origins: Wolverine is howling its way to the top of the box office with an opening day gross of $35 million. Bowing in 4,099 theaters, the film boasted a per-screen average of $8,539 on Friday. Ghosts of Girlfriends Past (starring Matthew McConaughey and Jennifer Garner) also scored a healthy opening-day number, with $5.8 million in 3,175 theaters. Wolverine's opening-day haul lags behind 2006's X-Men: The Last Stand's single-day opening gross of $45 million, according to Hollywood.com's box office analyst Paul Dergarabedian. Whether the can make up the deficit in the next two days remains to be seen. If not, it's highly unlikely the Hugh Jackman flick will manage to match Iron Man's gross of $98.6 from this same weekend last year.