Americans generally are richer, with more money to spend on extras, but they're giving a smaller proportion of it to their churches.

That's the central finding of a broad study comparing real income gains, adjusted for inflation and taxes, with changes in church contributions over a 17-year period."For the first time in history," says researcher Sylvia Ronsvalle, "the majority of people in the U.S. have discretionary income, beyond basic needs. However, church giving has not reflected this newly available money."

Much of it goes into the leisure industry, which soaks up 12 percent of the average American's income, with billions spent on cut flowers, pets, lawns and microwave popcorn, the report says.

It's apparently difficult to convince most church members that "meeting domestic and world needs in Jesus' name is as satisfying as taking a beloved pet to a doggie restaurant or even buying cut flowers," it says. "However, as a starting point, we ought to be able to portray increased stewardship as exciting as microwave popcorn. And grow from there."

The study by "empty tomb inc.," a non-profit research and service organization in Champaign, Ill., under a grant from the Lilly Endowment Inc., offers comparative data from 31 Protestant denominations and Roman Catholicism.

It found that Protestants in 1968 gave an average of 3.05 percent of their after-tax income to churches. That shrank to 2.79 percent by 1985.

Nevertheless, the average per capita amount given, in terms of constant 1982 dollars, was up from $247 in 1968 to $296 in 1985. Among evangelical denominations, the latest per capita was slightly more - $306

Among Catholics, average per capita giving declined from an average $232 in 1963 to $151 in 1985 - from 3.4 percent to 1.4 percent of income.

However, disposable income increased 103 percent, or $2,511 per capita, between 1968 and 1985, the report says.