Through April 11, box office is down a staggering 23% from 2010.  That's partially because "Avatar" was factored into last year's cume, but there has also been a dearth of big hits this year.  So far, only two movies that debuted in 2011, "Rango" and "Just Go With It," have made over $100 million compared with "How To Train Your Dragon," "Shutter Island," "Clash of the Titans" and "Valentine's Day" at this time in 2010.  Theater owners and studios are incredibly worried that audiences have been so turned off by the offerings this winter and spring that they won't return in force when summer movie season starts.  Therefore, don't be surprised if you see a big sigh of relief all across town if "Rio," "Scream 4" and "Fast Five" do big business to get movie fans back in the swing of things.