I don’t have a source to back this up, but I’d say 99% of all commercial jets are “leased”. The question is who holds the lease. I don’t believe it’s usually the manufacturer, far far more often it’s a “holding company” that’s associated with the airline. There’s extensive articles on the web that go in depth about why airlines don’t directly own their planes and rather lease from a holding company, but Tl;dr it’s mostly due to bankruptcy and tax reasons.