The Commerce Department said Tuesday that new home sales climbed 11.6 percent last month to a seasonally adjusted annual rate of 481,000. The growth in December pointed to rising sales in 2015, buoyed by the combination of strong hiring in recent months and drastically lower mortgage rates. Last year disappointed in part because builders largely focused on higher-end houses, which limited the number of would-be buyers and kept the pace of construction below historic levels. The National Association of Realtors said last week that sales of existing homes rose 2.4 percent last month to a seasonally adjusted annual rate of 5.04 million.