Stevie's changing recorded vocals

[petep9000]

I'm curious on what people's thoughts are about Stevie's recorded vocals through the years. Name some 'milestone' periods where there was a dramatic change in her vocals. I'm thinking from the BN album through Rumours her voice itself is pretty static and rather it is her singing style that evolved. I think the Tusk album was a major dramatic change in terms of I guess 'pitch' or 'timbre'. (note, I know nothing about professional voice, I'm just winging it here).

The Tusk and Belladonna vocals seem pretty consistent, but then Mirage it changes again. A bit deeper, even more vibrato, and some nasal element.
TWH is to me a continuation of the Mirage voice, which then plunged into something much more of a raspy, shuddery, throaty roar on RAL. This continued into TITN, except it almost seemed she was losing control of the wildness and was going with whatever popped out of her mouth ("Emmiline"!) and it's no secret that I'm rather fond of that.

And then what? Can we point to where 'old Stevie' became 'current Stevie'? Was it as early as 'No Questions Asked'? Earlier?? Was 'WTTR...S' an 'old Stevie' vocal or a 'new Stevie' vocal? Or, did it not emerge until TOSOTM?
Is it still morphing, or is it now static? Opinions?