GENEVA: The share of women in the world's parliaments has risen to a new high topping 20 percent, with quotas driving the surge, the International Parliamentary Union said Tuesday.

"Since parliaments exist, this is the first time in history that there's been one woman for every four men," said Anders Johnsson, head of the Geneva-based IPU, which groups 162 national legislatures.

The global average share of women in parliaments stood at 20.3 percent in 2012, up from 19.5 percent in 2011, the IPU said, ahead of the UN-sponsored International Women's Day on March 8.

Of the 48 countries which held elections last year, 22 used quotas of some form, including Senegal, Algeria, the Netherlands, France and South Korea.

Where quotas were set down in law, women took an average 24 percent of the seats, while voluntary quotas produced a rate of 22 percent.

In countries without a quota, women took just 12 percent of seats.

"Although quotas remain contentious in some parts of the world, they remain key to progress on a fundamental component of democracy -- gender parity in political representation," Johnsson said.

Johnsson said research showed that a "critical mass" of 30 percent was needed for women to influence the legislative process.

"When you have those kinds of numbers, the agenda tends to change. I'm not talking about a women's agenda, but a gender perspective," he explained.

"Women have, without over-generalising, a social awareness that many men don't have. And therefore they tend to bring what we could call a different social perspective. It doesn't matter if it's health or education, or defence, for example, or finance and the economy," he said.

"Having equality in parliament is not only about fulfilling a right, but also about doing things the right way. When one excludes a large proportion of the population, and doesn't include them in the decision-making process, it's not to the benefit of the country," he underlined.

Nordic countries, have long boasted the world's highest proportion of women in their parliaments, had an average of 42 percent in 2012.

Europe's overall rate was 23.2 percent, behind the Americas' 24.1 percent.

Women accounted for 20.4 percent of Sub-Saharan Africa's lawmakers, and for 17.9 percent in Asia.

In the Pacific, the figure was 15.3 percent -- and just three percent excluding Australia and New Zealand.

Arab states trailed with 13.2 percent, the IPU noted, saying the region had failed to deliver on the promises of democratic change heralded by the Arab Spring.

The notable exception was Algeria, with 31.6 percent, thanks to its quota.