I don't know all the stats in detail, as my DH researched it all himself. He thought (and he has a background in stats) that there is a difference depending on what type of vasectomy, and which surgeon. The private one who did his - no-scalpel technique - has every patient fill in forms some months after and the level of ongoing pain was just a few percent. Even then, almost all reported as mild.
DH also spent time browsing forums (on Reddit or somewhere like that, I'm guessing) and reading men's experience of this chronic pain. Lots of them were reporting it as severe and chronic, but it was only happening for a few seconds after exercise, or whatever. So even within the smaller "Severe, ongoing" pain group, it wasn't always constant.
Clearly there are cases of severe, chronic, constant pain, and that's terrible for those concerned. But he felt confident that it wasn't a 1/7 risk of severe, chronic, constant pain, like some of his friends fearfully told him (he was the first in his groups of friends to get a vasectomy).
As he said at the time, he gets severe pain intermittently from an injury sustained during tennis. It doesn't stop him playing tennis because he loves it more than he minds the pain. Even more so for sex... (Though thankfully he didn't experience any pain at all.)