Starting this month, the Florida Office of Insurance Regulation is going to begin surveying Florida property insurers about their experience with sinkhole claims, in an effort to get to the bottom of the simmering controversy over whether there really are more sinkholes in the Sunshine State these days. Property insurance premiums in Florida have been rising. After being held in check by the Office of Insurance Regulation in 2008, since January 2009, 140 insurers have been allowed to raise their rates, in some cases by more than 30 percent.