Trust Level ( NIS 2012 )

If I open NIS and go to "Advanced", I see at the bottom right TRUST LEVEL 57%

 

Now if I open Reputation Scan it shows "Files to Skip 57%" - so far so good.

 

Now I run the Reputation Quick Scan, and then it shows "Files to Skip 94.8%"

 

If I then go back to the "Advanced" page, it still shows 57%

 

(I had previously done a Reputation Full Scan, and results in the log show Files and Directories 6851, Trusted Files 6512 )

 

So what does that 57% mean and why doesn't it change?? Come to think of it, 6851 does not seem like enough files for Full Scan.