Metro’s annual payroll swelled by nearly 12 percent in the past three years to $765.2 million in fiscal 2006 — or nearly 70 percent of its $1.1 billion operating budget — as the transit agency hired 447 new workers over the same period, officials said.

Metro now has 10,503 employees on its payrolls, up from 10,056 in 2004 and 9,254 in 2000, officials said. Ridership has increased by nearly 16 percent over the same period.