Percentage of line waiters/non owners that have been invited?

Most of them.
It really depends on your region. I'm in Texas. Reserved in person about 1 hour after the store opened. I still have not received my invite. (Checking my account daily).
As I understand it, depending on delivery center capability, some areas (such as California) are much further down the line of inline non-owner reservation holders.

I'd recommend looking at the spreadsheet and comparing others in your area.