RICHMOND The surprising 200,000 net gain in December payrolls was “a heartening sign of a potential firming trend,” said Richmond Federal Reserve Bank President Jeffrey Lacker on Friday. In a speech to financial service professionals, Lacker said he expects only modest improvement in the economy in 2012, with economic growth expanding at a 2.0 to 2.5% pace. Lacker said the inflation outlook is “reasonably good right now” but said the risks were “tilted to the upside.” Still, there is a chance that inflation could fall well below the Fed’s implicit target of 2%, especially if global growth should soften enough to ease pressure on commodity prices. Lacker noted that the U.S. economy is now running on a lower-trend line than the 3% growth trend rate that persisted over the last century and a half. The over-built housing market “tops the list” of factors hampering the recovery, he said. And while much progress has been made in adjusting to the post-financial-crisis environment, the housing market still has “substantial adjustment” ahead.