SSPV is plainly schismatic, so is simply not Catholic. Indult masses are still performed by N.O. priests in N.O. churches, so are part of the N.O. church. Note that the first thing that happens any of the several times an idult priest gets caught having sex with boys, the first thing every one points out is "Oh, they're N.O. priests."
That leaves SSPX as being the prinary Catholic, but not N.O. group. I was decidedly leaving the SSPX as part of the Catholic church, so I wasn't trying to start a debate about them, but finding them insignificant in the grand scheme of things.
SSPX can claim high attendance levels for the simple reason new Protestant churches can: almost by definition, their members attend church.
Ah but those Protestant churches can't claim vocations. Out of 280 or so families, St. Jude's Chapel in PA has 7 vocations.