Since signs emerged last year that Americans were using fewer medical services, the question has been when we would flock back to clinics and hospitals. The answer: not yet. With four big insurers already done announcing earnings, there are scant signs of an uptick in what health experts call "utilization." UnitedHealth Group, the biggest health insurer by revenue and first to report, did note "some evidence" of increased doctor visits and outpatient services, but said they were still quite a bit less than expected and hospital stays were down. WellPoint, the second to go, said overall use of medical services has been "stable to declining" except for pharmacy, which was modestly up.