longs consider the finra short volume to be most accurate but such has been hotly debated in thousands of pages- mm's have at least a dozen ways to hide the true number of shorts -see e.g posts by 4kids9pets- so nobody knows the true number of shorts,even without naked shorts.
There's also tape vs non-tape (non-accounted for shares in many totals) etc.

there are charts of the daily tape short volume as I think you are aware which i just looked at


http://r.search.yahoo.com/_ylt=A0LEVi2FYd1Xlt...HdOugUHPM-