I think the emphasis was just too short. I think they're saying manufactured homes were 50% of Single Family Homes. Of all housing constructed some is Single Family Homes, a free standing detached residential building. This is distinct from attached residential housing like duplexes, condos, and apartments.

If you build 50 duplexes and 50 SFHs you've got 150 residences. If 50% of the SFHs are manufactured homes then you've got 25 manufactured homes out of 150. If the article is correct there's erroneous claims that manufactured homes are 60% of new "houses" which with my made up numbers would mean there's 90 manufactured homes out of our 150.