NEW YORK (THOMSON REUTERS FOUNDATION) - A record 5.6 per cent of Americans - or 18 million people - are lesbian, gay, bisexual or transgender, a Gallup poll found on Wednesday (Feb 24), attributing a significant increase to greater social acceptance.

The 2020 survey showed a 24 per cent rise from the last poll in 2017, when 4.5 per cent of adults identified as LGBT+.

The increase was largely driven by Generation Z adults - aged 18 to 23 - 15.9 per cent of whom said they were LGBT+.

"At a time when Americans are increasingly supportive of equal rights for gay, lesbian and transgender people, a growing percentage of Americans identify themselves as LGBT," Gallup said in a blog post.

The 2020 US election saw Pete Buttigieg run as the first openly gay presidential candidate and LGBT+ candidates scored numerous historic wins, including Sarah McBride as the first openly trans state senator.

Support for same-sex marriage, legalised in 2015 and largely seen as synonymous with backing for LGBT+ rights, has risen to 62 per cent of Americans, according to the Public Religion Research Institute, compared with 36 per cent in 2007.

The majority of LGBT+ Americans - 54.6 per cent - identify as bisexual, Gallup found, while 24.5 per cent said they were gay men, 11.7 per cent lesbian and 11.3 per cent trans.

The pollsters surveyed a random sample of 15,000 Americans throughout 2020 by telephone and found that 86.7 per cent identified as heterosexual, while 7.6 per cent declined to answer the question, up from about 5 per cent in previous Gallup surveys, which began in 2012.

There were marked differences between the generations. Older people were far less likely to consider themselves LGBT+, with the lowest percentage - 1.3 per cent - among those born before 1946.

Women are more likely to identify as LGBT+ than men, at 6.4 per cent compared with 4.9 per cent, researchers found, while 13 per cent of political liberals said they were LGBT+ versus 2.3 per cent of conservatives.

A similar trend has been witnessed in Britain, where the proportion of people who identify as lesbian, gay or bisexual increased to 2.2 per cent in 2018 from 1.6 per cent in 2016, according to government data.