It seems that the number being displayed in the microphone levels is some sort of translation of the actual value being stored. I found this by using a separate piece of software, which displayed a different value.
Well the first thing you should always do is right-click the "88" percentage and select "decibels" and always use that instead.

The percentage numbers are meaningless and map to different dB in different Windows versions, but the dB level should be defined by the hardware and should always map to the same signal level in any OS. Do the levels for a given decibel number match the
levels on other OSes for the same decibel number?
There is a solution in my video for this, however, it requires buying separate software :( You can use it for 14 days free. If anyone finds something similar that doesn't require you to pay money for, please please, add them to this thread ;)
Volumouse is freeware and will let you adjust the mic volume over its entire range, in small steps.