The first-gen/second-gen language is a bit odd. More common would be “mild” vs. “full” hybrid, but most hybrid cars sold, in the US at least, are full hybrids (what you call “second-generation” hybrids); Toyota Prius nameplates alone account for almost half of all hybrids that have been sold in the US, and all of those are full hybrids.) It may be that mild hybrids dominate if you are counting individual models, but certainly not if you are counting vehicles.