SINGAPORE (Reuters) - Crude oil futures fell on Monday, with U.S. futures touching levels not seen since 1999, extending weakness on the back of sliding demand and concerns that U.S. storage facilities will soon fill to the brim amid the coronavirus pandemic. The oil market has been under pressure due to a spate of reports on weak fuel consumption and grim forecasts from the Organization of the Petroleum Exporting Countries (OPEC) and the International Energy Agency. The volume of oil held in U.S. storage, especially at Cushing, Oklahoma, the delivery point for the U.S. West Texas Intermediate (WTI) contract, is...