Over all the percentage is low. ORA has a nice captive breeding program and a few other vendors. Designer and non designer clowns are pretty easy to find. Cardinals, a couple Basslet types, Sea Horses, one type of Mandarin, recently some Tang types but not widely available.
Spawning is not the issue, it's rearing the larvae that is difficult.
Totally agree going from egg to lfs is the issue with most. But hopefully it will continue to get better success rates as breeders and hobbyist try. There's always breakthroughs and many we have bred still only been more recently. 25 years ago we didn't have the options we do now at all. So it is getting better just slowly as nothing good happens overnight in reefing.