About 1.6 million people who signed up for coverage this year under President Barack Obama’s health care law dropped out by the end of March, according to administration figures released late Thursday. The report from the Health and Human Services department said some 11.1 million people were still signed up. But that’s a drop of nearly 13 percent from the 12.7 million who initially enrolled for subsidized private coverage this year. Those dropouts failed to seal the deal by paying their premiums. …