LONDON/MOSCOW (Reuters) – A plunge in the oil price to 12-year lows during Russia’s New Year and Orthodox Christmas break means the country returns to work on Monday with its economic recovery and once-mighty savings war chest on the line. Crude’s collapse from $100 a barrel since mid-2014 has already pummeled Russia, which relies on energy for about half its budget revenues and 40 percent of its exports. The latest slide compounds the problems facing President Vladimir Putin ahead of elections in 2018.