The problem here is if hardware and algorithms for static analysis are improving at linear pace, applications are growing at least exponentially (if we add-in 3rd party libraries).
I would say that the best economic value is being delivered if we consider some code fragments that are almost never covered by tests (any of them) - like error detector.
Guys at pvs-studio brought in some pretty funny example of such errors: http://www.viva64.com/en/a/0078/