There were 119,188 marriages in Australia in 2018, including 6,538 same-sex marriages, according to data released by the Australian Bureau of Statistics (ABS).
James Eynstone-Hinkins, Director of the ABS Health and Vital Statistics Section, said 2018 was the first full year in which same-sex couples could marry after changes to the Marriage Act in late 2017.
"In 2018, same-sex marriages represented 5.5 per cent of the total number of marriages and inclusion of these marriages has influenced some key statistics," said Mr Eynstone-Hinkins.
"The median age at marriage recorded the greatest increase in more than a decade. This was largely because the median age of same-sex couples was considerably higher than that of opposite-sex couples."
The median age of same-sex couples in 2018 was 44.9 years for males and 39.3 years for females (compared with 32.1 years for males and 30.2 years for females for opposite-sex couples).
Although more than one-third of same sex marriages occurred in NSW (35.0%), same-sex marriages accounted for only 5.6% of all NSW marriages. The jurisdiction with the highest proportion of same-sex marriages was the Australian Capital Territory at 8.3% of all marriages.
The data was released as part of Marriages and Divorces, Australia, 2018 which also showed that the most popular season to marry was spring (31.8 per cent of all marriages), and the most popular day to marry was Saturday 20 October, with 1,993 couples tying the knot.
The information also showed that there were 49,404 divorces in Australia in 2018. The crude divorce rate was 2.0 divorces per 1,000 people in 2018, compared to 2.7 in 1998.
