Approximately zero. And obviously, those would have been covered under warranty.

The reason you haven't heard this before is that it didn't happen.

Apple did not consider "my (friends) phone has been throttled because of the battery" as sufficient cause to replace the battery under warranty.

They weren't covered under my warranty.

It was covered under my warranty.

Either the warranty expired -- in which case it isn't a "few months", or it was within the warranty period, in which case it is covered.

Nope. Less than 8 months old. Battery was too degraded to run as normal, but didn't pass the threshold for replacement.

https://news.ycombinator.com/item?id=25144122

But don't take my word for it. RTFA. This lawsuit was settled because of the exact scenario I described.

Not sure in terms of numbers, you might be able to find it if you dug through the court documents. It's not a rare anecdote though, for instance see this comment currently slightly below this thread: https://news.ycombinator.com/item?id=25144122