The number of gay and lesbian couples living together throughout America has risen sharply over the past decade, new census data shows.

Figures released this week by the Census Bureau and analyzed by Gary Gates, a scholar at the Williams Institute at the University of California at Los Angeles, a think tank which studies the effect of policy on LGBT people, show the number of self-identified gay couples grew by 52% over the past decade.

The Census Bureau does not ask people whether they are gay; however, starting in 1990 the agency included questions that allow respondents to identify themselves as living with a member of the same sex, although the status of their relationship is not questioned.

The figures show a nearly 90% increase in Montana, Nevada and West Virginia. More traditional gay-friendly states such as California, New York and Washington D.C. saw more modest increases of 40% of less.

Gates told The New York Times that he did not believe there had been a sudden surge of gay couples. Instead, gay people are increasingly feeling more comfortable answering the question.

The wider trend, Gates said, is that acceptance of gay couples is moving beyond coastal states.