German retail sales plunged by a provisional 2.8 percent in May from the previous month, after a revised reading of no change in April, data released on Thursday by the national statistics office showed. The figures are an indication that Europe\'s biggest economy is cooling following strong growth in the first quarter of 2011. Analysts polled by Dow Jones Newswires had forecast a monthly gain of 0.5 percent in May after an initial estimate by the Destatis office had suggested a gain of 0.6 percent in April.