Gay marriage legislation cleared federal parliament in December 2017 after 61.6 per cent of participants in an Australia-wide voluntary postal survey backed the change.

A total of 6538 same-sex marriages took place across the country in 2018 out of 119,188 weddings, the ABS figures released on Wednesday reveal.

NSW had the highest number of same-sex marriages, with 2290 couples tying the knot, while the ACT had the highest proportion, with 8.3 per cent of all weddings in the territory last year involving same-sex partners.

Liberal City of Sydney councillor Christine Forster - who married her partner Virginia Flitcroft in February 2018 - says there would have been "pent up demand" for same-sex weddings.

"We were like that - we'd been wanting to get married for many years," Ms Forster told AAP on Wednesday.

"I'm sure there were a lot of long-term couples who would have liked to have gotten married in years preceding but weren't able to. So once the law changed there probably was a bit of a rush."

Over the next few years the numbers might drop slightly, Ms Forster said, but wanting to partner up is part of being human.

"Wanting to make that special relationship that human beings have ... and recognise it as a committed, long-term, special relationship is part of the human condition.

"I suspect that as we go on the numbers will be pretty reflective of the broader population."

Ms Forster says allowing same-sex couples to get married changed Australia and her relationship for the better.

"It has been a very positive thing for the country as a whole and certainly a very positive thing for me personally.

"It is a different relationship (with Ms Flitcroft) now than it was before we got married."

Australia-wide 57.8 per cent of same-sex marriages in 2018 were female couples while 42.2 per cent were male couples, the ABS says.

Some 98.9 per cent were married by a celebrant with just 1.1 per cent married by a religious minister.

Rodney Croome, a spokesman for advocacy group just.equal, says the statistics show that "marriage equality was never an ideological crusade".

Rather it was a "heartfelt aspiration for equal dignity and belonging that was widely-shared by LGBTI people and our families," he said in a statement.

SAME-SEX MARRIAGE ACROSS AUSTRALIA IN 2018:

Australia: 6538 (5.5 per cent of all marriages)

NSW: 2290 (5.6 per cent)

Victoria: 1655 (5.5 per cent)

Queensland: 1292 (5.5 per cent)

South Australia: 387 (5.0 per cent)

Western Australia: 600 (4.9 per cent)

Tasmania: 143 (5.7 per cent)

Northern Territory: 47 (5.9 per cent)

ACT: 130 (8.3 per cent)

Australian Associated Press