Now if you wanted to change the question to ElectrifyAmerica stalls, I'd have to answer 12.5% (1 out of 8) waiting FOR a stall (waited about 30 minutes -- 4 stalls and I arrived with 2 waiting ahead of me), and 37.5% (3 out of 8) waiting AT/FOR a stall.
One of the additional waits was due to a technical glitch moving from one stall to another after the first stall was charging slowly (I think the network didn't completely terminate the previous charging session and wouldn't let us connect to the new one). This actually ended up being a frustrating 45 minutes on the phone with customer service.
The other wait was due to visiting a site that had literally just opened about 2 days earlier and wasn't in the EA app yet. Another 30 minute wait with customer service who was having trouble finding the station on their end as well. I guess it's a bit unfair to hold this against them as the next day it was in the app, but still...
I know this is not what you were asking about, but nonetheless it's interesting to compare the Tesla experience with the non-Tesla experience.