BOSTON — Small businesses in greater Boston lost 74.9 percent of revenue during the coronavirus shut down as of April 25, according to Harvard University’s Opportunity Insights Economic Tracker.

That was more than most other major metropolitan areas in the U.S. and nearly twice as much as the national average of 39.8 percent. Harvard created the tracker to measure the economic impact of the COVID-19 crisis.

Small businesses in New Orleans, which lost 83.8 percent of revenue, and Washington, which lost 76.7 percent of revenue, were the only metro areas where small businesses were hit worse than those in greater Boston.

The data covers small businesses covers Suffolk County, which includes Boston, Chelsea, Revere, and Winthrop.

The big losses in Boston partially stem from the high number of confirmed cases in Massachusetts. But New York, Seattle, and Los Angeles — three regions hit as hard or harder by the new coronavirus than Massachusetts — all saw average small business revenue declines at least 13 percentage points lower than Boston’s.

On Monday, Massachusetts Gov. Charlie Baker outlined a plan to reopen the state economy in four phases. There is no timeline for the phases, which will be contingent on public health data progress. The reopening advisory board will release a report outlining details for specific industries on May 18.

“The process is complicated,” Baker said. “It’s gradual and it requires an incredible amount of patience.”