MONTPELIER, Vt. – New England continues to lag the nation in charitable giving, with upper-income Vermonters and Mainers showing a decline in generosity during the 10 years ending in 2004, according to a study based on federal tax data.

“If those people who are below the national average would give to the average, there would be a lot of money generated into the philanthropic pie,” said Martin Cohn, spokesman for the Catalogue for Philanthropy, which compiles an annual “generosity index.”

The Needham, Mass.-based nonprofit group issues its annual ranking of states and their residents’ charitable giving by using Internal Revenue Service data showing average adjusted gross incomes and average itemized charitable giving.

In 2004, the most recent year for which data were available, New Hampshire ranked at the bottom among states for charitable giving. All other New England states were in the bottom 10, with the exception of Maine, which ranked 33rd.

Cohn called the tax data a “crude” tool with which to examine charitable giving, and not everyone agrees with his group’s consistent finding that New England states tend to be less generous than the nation as a whole.

Last year, a group of philanthropic groups around the region issued its own report based on survey data, painting a more positive picture of giving by New Englanders. It said only about a third of taxpayers itemize charitable contributions, so a study based on IRS data presents an incomplete picture.

The New England charities’ report said the main difference between residents of the region and people nationally is that New Englanders give less to churches and other religious organizations.

Based on survey data from the Center on Philanthropy at Indiana University, the New England charities’ report said that “in New England, donors give a lower percentage of their income to religious causes and about the same percentage to secular causes as do donors elsewhere in the U.S. The difference in the total is largely attributable to the difference in religious giving.”

The Catalogue for Philanthropy study confirmed that Bible Belt states have been the most generous relative to their residents’ incomes, with Alabama, Arkansas and Mississippi typically landing in the top five.

This year’s report by the Catalogue For Philanthropy was the 10th annual report issued by the group; Cohn said that would allow a good look at trends. “States can look not only at how they’re doing compared to other states, but how they’re doing when compared with themselves.”

The report provided statistics for all taxpayers in each state and a separate set for those with an adjusted gross income of more than $200,000.

One thing was striking among the upper income group: Relative to their wealth, they are less generous than the population as a whole. The average upper-income person nationwide donated 3.8 percent of adjusted gross income to charity in 2004; overall, tax filers reported giving 7.9 percent of their adjusted gross income to charity.

In all six New England states, giving as percentage of income for people making more than $200,000 came in at below the national 3.8 percent figure. Between 1995 and 2004, Maine posted a slight decline in that category, and Vermont saw a larger decline. In 1995, Vermonters making more than $200,000 gave about 4.2 percent of adjusted gross income to charity; by 2004, that had declined to 3.5 percent.

Average 2004 adjusted gross incomes for those making more than $200,000 in New England ranged from $661,000 in Connecticut down to $458,000 in Vermont.

Average adjusted gross incomes for all taxpayers ranged from $73,073 in Connecticut in 2004 down to $42,507 in Maine.