The economy has been growing since 2009, but more slowly and inconsistently than many Americans would like and many economists and policy makers had predicted. President Obama has made the economy’s condition his main focus this summer, promising new efforts to encourage economic growth, including a series of proposals on higher education that he is expected to announce Thursday. While taking credit for some improvement in the economy, he has acknowledged that many Americans have yet to see the benefits.

“We’ve got more work to do,” Mr. Obama said last month at Knox College in Galesburg, Ill. “Even though our businesses are creating new jobs and have broken record profits, nearly all the income gains of the past 10 years have continued to flow to the top 1 percent. The average C.E.O. has gotten a raise of nearly 40 percent since 2009. The average American earns less than he or she did in 1999.”

In the recession and its aftermath, many people went back to school, earning associate or bachelor’s degrees. Such credentials have helped, the new data shows, but they have been no guarantee against loss of income.

Households headed by people with only a high school diploma have seen their post-recession income decline by 9.3 percent, to $39,300 in June of this year, the report said. For households headed by people with an associate degree, median income declined by 8.6 percent in those four years, to $56,400. And among households headed by people with a bachelor’s degree or more, median income declined by 6.5 percent, to $84,700.

Since the end of the recession, the report said, income has declined by 3.6 percent for non-Hispanic white households, to $58,000, and by 4.5 percent for Hispanic households, to $41,000. Those changes were smaller than the 10.9 percent decline, to $33,500, for non-Hispanic black households, whose economic problems are likely to be a focus when Mr. Obama speaks next week on the 50th anniversary of the March on Washington.

Median income for households headed by people ages 65 to 74 increased by 5.1 percent, to $43,000, even though in many cases the head of the household was retired. By comparison, median income for households headed by people under age 25 fell 9.6 percent, to $31,300.

Median income declined by 4.5 percent for households headed by a person 25 to 34 years old, by 5.7 percent for those 35 to 44, by 2.5 percent for those 45 to 54, and by 7 percent for those 55 to 64. The report found no significant change for households headed by a person 75 or older.