I believe the 'auto squelch' option on this radio only affects the AM/FM modes and the manual squelch all modes?
Makes sense really as SSB really isn't somewhere you'd want to be using squelch anyway but would save your ears from AM/FM detector hash should you switch modes forgetting the manual squelch is set to minimum.
As to what 'levels' they switch at your guess would be as good as mine. You could always hook up a calibrated signal generator to find the specific microvolt range but I'll bet it's different for each radio and doesn't step exactly as you'd like or believe.
If the manual squelch control is '1' as minimum and '36' as maximum I'd assume the auto squelch would follow the same convention with '9' as the maximum.
I think the ASQ auto-squelch is just another sales ploy rather than anything really useful......like all those NB/ANL switches that did absolutely nothing on many radios of old!
All the best,