The average price for regular gasoline at filling stations in the United States fell 11.22 cents to about $3.63 a gallon, according to the Lundberg Survey, a market research company.

The price covers the two-week period that ended Friday and is derived from a survey of about 2,500 filling stations nationwide by Trilby Lundberg. She said that prices had dropped 37.2 cents a gallon since they hit almost $4 a gallon on average on May 8.

“The rate of decline was reduced in the latest two weeks, but we have yet to see the impact of the government sale of crude,” Ms. Lundberg said Sunday.

Prices have fallen after member countries of the International Energy Agency said last week they would release 60 million barrels of oil from emergency stockpiles and on concern that the United States and European economies are weakening.