With optimism building that the United States is already recovering smartly from another horrible start to the year, focus will shift this week to reports that may show the euro zone is finally shaking off half a decade of torpor. The 19-member currency union has been a millstone around the global economy’s neck ever since the financial crisis spawned a sovereign debt crisis particular to Europe. So it is all the more crucial for more than just its citizens suffering from years of high unemployment and feeble or no growth that Europe is able to pick up some of the slack.