The number of homeowners who have refinanced their home loans under a revamped federal program for those with sunken property values is rising, but the effort is just starting to reach the most severely “underwater” borrowers. Statistics released Friday by the Federal Housing Finance Agency show that more than 41,000 homeowners who owe more than 105% of their home’s current value completed refinances through the government’s Home Affordable Refinance Program in the first quarter of this year. That was more than triple the level in the final quarter of last year. But so far, relatively few homeowners who are deeply underwater have completed the refinancing process. Only about 4,400 homeowners who owe more than 125% of their home’s value have refinanced under HARP to date. Officials at FHFA expect that number to grow once those loans can be packaged into mortgage-backed securities, a process that’s expected to be complete this summer. The Obama administration and the housing regulator, which oversees mortgage giants Fannie Mae and Freddie Mac, rolled out several changes last fall that were designed to make more refinances happen. Before those changes, Fannie and Freddie’s borrowers were blocked from refinancing if they owed more than 125% of their home’s value.