International women's day: Which nation has smallest pay gap for women?

Several European nations boast smaller pay gaps than the United States, says a new study released on International Women's Day.

Women in the United States have made big strides in reducing the wage gap with men over the past three decades, but pay for women in other industrialized nations is a little more egalitarian on average.

While America’s wage gap is much smaller than South Korea’s and Japan’s, US women still earn nearly a fifth less than their male counterparts. On average among all industrialized nations, women earn about 18 percent less than men despite recent employment rate gains, according to a report the Organization for Economic Cooperation and Development (OECD) released Monday to coincide with International Women’s Day.

South Korea has the biggest wage gap at 38 percent, followed by Japan at 33 percent.

Belgium has the smallest wage gap: 9 percent. Click below to see where gender-based wage differences are the biggest and smallest among 22 of 30 industrialized countries (Austria, Turkey, Mexico, Slovakia, Italy, Iceland, Luxembourg, and Norway were not ranked).

IN PICTURES: Top 10 developed countries where women make less than men

IN PICTURES: Top 10 developed countries where women's pay comes closest to men's pay

Unequal pay prevails in part because women are more likely to work in lower-paying jobs, which is caused in part because women in nearly all OECD countries spend at least twice as much time as men taking care of children or other relatives, according to the report.

Still, the wage gap does reflect an improvement from 25 years ago, when women earned 26 percent less than men among all OCED countries. The disparity was 32 percent in the US.

Women have narrowed the gap as their employment rates have risen. While fewer than half of all women aged 15 to 64 in OECD countries participated in the labor market in 1970, today nearly 60 percent of women work. Women’s employment is highest in Iceland, at 80 percent, and lowest in Turkey, at 22 percent. US participation is about 66 percent.

The report also shows a significant drop in birth rates, with most OECD countries falling below replacement rate. Only the US and six other countries exceeded two children per woman. At the same time, only the US does not provide statutory paid maternity leave.

The OECD report says that the US ought to enforce statutory paid maternity leave and all rich countries should enforce paid paternity leave to increase employment equality.

“As long as women rather than men take time off work to provide care, there will always be employers who perceive women as less committed to their career than men, and are therefore less likely to invest in female career opportunities and depress female earnings as a whole,” the report states.

International Women’s Day has evolved into a global event celebrated annually on March 8, though it was started by socialist political organizations in the early 20th century.

This year, Women for Women International sponsored peace demonstrations on bridges in 70 locations, including in London where the wife of Prime Minister Gordon Brown, Sarah Brown, attended.

“We will not sow the seeds for a brighter future or reap the benefits of the change we need without the full and active participation of women around the world,” President Obama said in a statement Monday. “Today, Michelle and I remember, celebrate, and honor the sacrifices, talents and leadership of women around the world.”

IN PICTURES: Top 10 developed countries where women make less than men

IN PICTURES: Top 10 developed countries where women's pay comes closest to men's pay