Two months into the Washington Nationals' season, a larger percentage of the crowd than expected appears to be taking Metro to Robert F. Kennedy Memorial Stadium.

In the 22 home games in April and May, an average of 13,210 people took Metro to the stadium, and 12,351 took Metro home, according to data from the public transit service.

Meanwhile, an average of 3,786 automobiles have been parked in stadium lots, according to data provided by the D.C. Sports & Entertainment Commission.

Although city and transportation officials were not sure how many people would use Metro for games, they generally estimated 40 percent to 45 percent of the crowd. In fact, the percentage appears to be higher. An average of 25,323 fans entered RFK for the first 22 games, meaning Metro riders made up about 51 percent of the crowd.

Nigel Gragg, president of Park USA, which operates the stadium parking, said he had expected more cars at the games. The stadium, built to accommodate football crowds of more than 50,000, has about 9,000 parking spots. It costs $10 to park in stadium lots.

Metro, Gragg said, "is doing a good job, as they should, promoting the convenience and affordability of ridership. We might have expected more cars. The percentage of [Metro riders] is more than expected."

The trend started at the Nationals' first home game April 14 against the Arizona Diamondbacks. City officials urged fans to take Metro to the sold-out game, and about 27,000 did, far more than the 20,000 the transit service had predicted. On that evening, 3,771 vehicles were parked in the stadium lots.

The largest number of vehicles to date was recorded when a crowd of 35,760 entered the stadium for a Sunday game against the Chicago Cubs on May 15. A total of 5,588 vehicles were parked at the stadium, and a little more than 16,000 people rode Metro.

Although it is still early in the season, city and transportation officials are watching the figures closely because they will be used to plan construction of a stadium along the Anacostia waterfront.

Under the stadium agreement signed in the fall by Mayor Anthony A. Williams (D) and Major League Baseball, the stadium must have 1,100 parking spots. Where the rest of the cars will park is not clear.

The Baltimore Orioles have 5,000 parking spots surrounding the Camden Yards stadium and rent 3,000 more nearby.

District officials have said they believe that private developers will open parking lots and garages on land near the stadium site. City planners also are talking to developers to determine whether more spots than the required 1,100 could be built on the 20-acre stadium site, perhaps in underground garages.

Developers are coming forward with plans. One, by Herbert Miller, head of Western Development Corp., would add more than 5,000 spots on or near the stadium site. Those spots would be used for games but also to serve other development that is being proposed by Miller, including retail shops, restaurants and office buildings.

Another company proposed installing meters and charging fans to park on the street near the stadium. But D.C. Council member Sharon Ambrose (D-Ward 6), who represents the area where the new stadium is planned, has objected because she has heard from residents who worry that such a plan would disrupt their neighborhoods.