According to Australian Social Trends 2008, the annual release of data from the Australian Bureau of Statistics, more women are taking part in the workforce than 20 years ago, giving Australians a higher than average rate of participation in paid work.

But the bureau said once a person reached the age of 55, their participation tended to fall.

It cited 2004 Howard government policies such as the $500 tax rebate for mature-age workers over 55 years and the introduction of the child care tax rebate as contributing to increased participation in full or part-time work.

Women with young children tended to have a lower participation rate but were returning to the workforce more quickly than in the past.

It said the trend for women to delay child birth until later years, along with their propensity to combine work with family, meant the traditional dip in women's participation had become less pronounced.

The labour force participation rate for men changed little in the 20 years to 2006, increasing by 0.1per cent to 71.5 per cent.

But for women, the participation rate increased over the same period from 52.8 per cent to 58 per cent, while the involvement of men and women in part-time work increased over the 20 years.

The biggest growth has been in women aged between 55 and 64 years, whose participation rate in full and part-time work jumped 17 per cent to 48 per cent in the 10 years to 2006.

The increase was more modest among men in the same age group whose participation rose by 7 per cent to 68 per cent.

The bureau warned the barriers preventing about 1.7million people from entering the workforce or increasing the number of hours they currently worked needed to be lifted to ensure Australia was prepared for the economic challenges of an ageing population.

The bureau also reported trade union membership had been in freefall since the initial push towards enterprise bargaining began in 1987, with union membership falling from 46 per cent to 19 per cent in 2007.

Union membership rates remained higher among older workers and was strongest in the public sector and blue collar industries.