Maybe 75%?
I've gotten pointed to documentation I never would have found and I doubt a human would have found. I've had returns immediately processed rather than waiting 2 days for a RMA to show up in my email. I had a subscription rate lowered (my desired outcome) when I tried to cancel a service. And I've had a software bug escalated to the appropriate team within a couple of minutes. And all these interactions were probably 10x faster, at least, than they would have been with a human.
I love chatbots for customer service. Not because they save the company money, but because they seem to save me a ton of time (no more 20 minutes of hold, followed by being put on hold for 10 minutes multiple times), and they seem to follow policies more "objectively", and they escalate easily whenever they can't handle something. It just seems like more reliable and faster outcomes for "normal" support, and then you still get a real agent for more complicated situations.