OTTAWA, May 21 (AFP) - Canada's annual inflation rate soared to 1.7 percent in April, the highest since October 1997, a government agency reported Friday. Statistics Canada said the April increase in the consumer price index, up sharply from the March figure of one percent, was due primarily to transportation, with higher costs for gasoline, new cars, trucks and air fares. Also contributing to the increase were higher prices for shelter and food. These increases were partially offset by lower costs for computer equipment and telephone services. The April increase was the highest since October 1997, when it was 1.5 percent, Statistics Canada said.  