I have measured at which level each segment light up in the windows audio stack with Adobe Audition Aside and some tones injected.

Here are the values

10    -0.25 db
9    -1    db
8    -2    db
7    -3.25 db
6    -4.75 db
5    -6.5  db
4    -8.5  db
3    -11   db
2    -15   db
1    -22.5 db