A latest survey showed that Singapore trading firms have suffered the worst drop in the region amid the worsening global economy, though the overall outlook remained positive. The trade confidence index of banking giant HSBC showed that the reading for Singapore dropped by 16 points to 105, the biggest decline among eight Asia-Pacific markets covered by the survey in May, local daily Straits Times reported on Friday. A reading above 100 means that the outlook for traders is positive while one below 100 registers pessimism. Indonesia recorded a confidence index rating of 144. Willie Tham, HSBC managing director and head of commercial banking, said it was not surprising that companies in Singapore were turning more cautious given the global volatility. But over the longer term, Singapore\'s prospects remain bright and trading volumes are expected to soar 110 percent over the next 15 years, he said, adding that Singapore accounted for 2.2 percent of global trade now.