The private sector of the United States added the most jobs in a year in December, said a private survey released Wednesday. U.S. private companies added 238,000 jobs in December, the largest monthly gain since November 2012, said the National Employment Report released jointly by Automatic Data Processing ( ADP) and Moody's Analytics, based on a monthly survey. Economists were expecting an increase of 200,000 private jobs for December. "The job market ended 2013 on a high note," said Mark Zandi, chief economist of Moody's Analytics. "Job gains are broad-based across industries, most notably in construction and manufacturing. It appears that business are growing more confident and increasing their hiring." In December, small and medium-sized businesses accounted for most of the employment gains, adding 167,000 jobs, while large businesses with over 500 employees added 71,000 jobs, according to the report. Employment in the construction sector rose by 48,000 jobs in December, the most since 2006, the latest evidence that the housing recovery gained momentum at the end of 2013. The service sector also added 170,000 jobs last month. For all of 2013, the private sector gained 2.16 million jobs, up from 1.96 million in the previous year, the report said. The ADP survey studied data from private businesses with more than 23 million workers on payrolls but excludes government job growth. The Labor Department will release its jobs report for December Friday.