The rapid growth of Florida's population is creating opportunities for the state's health insurers, who are targeting second-tier metropolitan regions such as Naples and Marco Island for new products and sales efforts. The commercial group-health HMO continues to decline in Florida as Medicare and Medicaid plans take on greater importance. Medicare Advantage HMO enrollment in the Sunshine State increased by 8.5 percent from December 2007 to February 2008, with Humana and WellCare Health Plans solidifying their positions as the top plans in that state. Meanwhile, health plans are re-engineering their formularies in light of the huge influx of drug patent expirations.