Less that 1 percent of the U.S. population lives to be 90, according to the Census Bureau.The percentage of the population that lives to be 92 and still works everyday is unknown, although one Warren County resident holds that distinction. It’s Leard Hitchcock, who can be found driving a tractor around his farm near Rock Island most days.“I tell people I’ve gotten to the age where I’m too old to retire,” said Hitchcock, who was born in Bone Cave in February, 1921. “I like to say I work 14 hours a day in the summer.