U.S. companies added more workers than projected in December amid rising optimism about the prospects for demand, according to a private report on payrolls. The 238,000 increase in employment was the biggest since November 2012 and followed a revised 229,000 gain in November that was better than initially estimated, concluded ADP Research Institute in Roseland, N.J. The December numbers exceeded the most optimistic forecast in a Bloomberg survey in which the median projection called for a 200,000 advance. A pickup in hiring, with rising wages, are helping to spur growth in consumer purchases. A Labor Department report this week may show private payrolls rose by 197,000 last month, according to the Bloomberg survey median.