WASHINGTON – People in this country have been volunteering at record levels in the years after the terrorist attacks of Sept. 11, 2001, but that voluntary service dipped slightly in 2006, a study found.

More than a fourth of the population, 26.7 percent, did volunteer work in 2006, down from 28.8 percent the previous year, according to a new report.

An increase in volunteerism from 20.4 percent in 1989 to 26.7 percent in 2006 was heavily influenced by a sharp increase – almost doubling – in the volunteer rates of young people ages 16-19, according to the report by the Corporation for National and Community Service. The report is being released at the start of National Volunteer Week.

Maine ranked 16th in the nation, at 33 percent.

“Out of the tragedy of 9-11 and the devastation of hurricanes has come an unmistakable good: a strong interest in volunteering and community involvement,” said David Eisner, chief executive officer of the corporation. But he said there’s plenty to be done to expand the country’s service to others.

The percentage of beginning college students who believe it is very important to help others in difficulty reached a 25-year high in 2005, the Higher Education Research Institute found.

But volunteerism rates have increased for most age groups over that time period.

The volunteer rate for seniors has increased from 16.9 percent in 1989 to 23.8 percent 2006. Volunteerism among adults ages 45-64 has also increased since 1989.

The overall volunteer rate was at 27.4 percent in 2002 and has stayed close to that level for the last five years.

The corporation, which administers volunteer programs including Senior Corps and AmeriCorps, prepared the report in partnership with the Bureau of Labor Statistics and the U.S. Census Bureau. The report is intended to help expand the ranks of volunteers and encourage people to continue that volunteer work.

About 61.2 million people volunteered in 2006, according to the study.

The study found:

. The number of volunteers serving in an education or youth services organization nearly doubled from 15.1 percent in 1989 to 27 percent in 2006.

. Religious institutions were the most popular organization choice among volunteers.

. On average, two-thirds of volunteers who served in 2005 continued to serve in 2006.

The top five states for volunteerism in the new report were Utah, Nebraska, Minnesota, Alaska and Kansas, with volunteer rates ranging from 45.9 percent in Utah to 38.3 percent in Kansas.

The lowest five were Mississippi, Florida, Louisiana, New York and Nevada with volunteer rates ranging from 24.2 percent in Mississippi to 17.5 percent in Nevada.

The study also looked at civic engagement in the country, including activities such as voting and neighborhood engagement. The top states for levels of civic engagement were Montana, Vermont, Alaska, South Dakota and Wyoming.