Construction of single-family homes in the United States cooled slightly in January after surging the previous month, but a rise in building permits suggested builders are growing more confident that more buyers are ready to enter the market, the government reported Thursday. The Commerce Department said builders began work on an annual rate of 699,000 homes in January, up 1.5 percent from December and nearly matching November's three-year high for housing starts. Construction began on 508,000 single-family homes last month, a 1 percent decline from December and the first drop in four months. A big gain in volatile apartment construction helped offset the drop in single-family homes. Building permits, considered a measure of future construction activity, rose 0.7 percent in January, with the majority of the permits for single-family homes. Single-family home construction rose in each of the last three months of 2011, bringing the pace of those housing starts to the highest level since April 2010. The modest but steady gains helped increase confidence among builders after the worst year for single-family home construction on record.