OTTAWA, June 24 (Reuters) - Confidence among Canadian exporters has surged to its highest level in more than 20 years, amid mounting optimism that a sustained global economic recovery is underway, a survey by Export Development Canada (EDC) showed on Thursday. EDC"s Trade Confidence Index jumped 19% from end-2020 to mid-2021, the largest 6-month increase since the survey began in 1999, the agency said. The recovery appears to be broad-based across all regions of the country, it said. "It"s just extraordinary that this kind of rush is happening. It"s really telling us that everybody is arming themselves for what"s coming in the second half of this year," said Peter Hall, chief economist at EDC. Canada"s economy - like those of many of its global peers - is set to boom in the second half of 2021, as widespread public vaccinations allow businesses to reopen and consumers begin to dip into their pandemic savings. A strong rebound south of the border is also expected to help. A growing share of companies reported orders from customers in the United States, Canada"s largest trading partner, had improved in the past six months, EDC said. And 65% of respondents said they are planning to export to new markets, with the UK and Australia top destinations. Exports account for about a third of Canada"s gross domestic product. But concerns remain, notably the strong Canadian dollar - which hit a six-year high earlier this month - and mounting worries over trade protectionism, especially U.S. President Joe Biden"s "Buy American" plan and fraught China-Canada relations. The survey was conducted between April and June, spanning a period that saw fresh lockdowns amid a harsh third wave of COVID-19 infections followed by the early stages of reopening.