UPDATE 1-Chile copper export revenue at 4-yr high but trade surplus shrinks

(Adds lithium exports and background) SANTIAGO, June 7 (Reuters) - Chilean copper export revenue hit its highest level in four years as crunch wage negotiations with workers at the country's biggest mine sent prices to a 2018 high, central bank data showed on Thursday. Even so, the world's leading copper producer's trade surplus fell by more than 30 percent to $679 million in May from $983 million in April. Analysts attributed the drop to firmer import revenue due to high fuel pri