About 45.8 million people around the world are trapped in modern versions of enslavement, a human rights group reported Tuesday, 28 percent more than it last estimate two years ago.

The organization, the Walk Free Foundation, attributed the increased number in its report, the 2016 Global Slavery Index, to improved data collection and research methodology. Whether enslavement is increasing or decreasing remains unclear.

The organization said it had derived the index from 42,000 interviews conducted in 53 languages. Some form of modern slavery exists in all 167 countries covered by the index, it said.

Unlike historical definitions of slavery in which people were held as legal property, a practice that has been universally outlawed, modern slavery is generally defined as human trafficking, forced labor, bondage from indebtedness, forced or servile marriage or commercial sexual exploitation.

The Walk Free Foundation's report said more than half the population of modern slaves are in five countries - India, with 18.35 million, China, with 3.39 million, Pakistan, 2.13 million, Bangladesh, 1.53 million, and Uzbekistan, 1.23 million.

The report found that North Korea had the highest per capita level of modern slavery, at 4.37 percent of the population, followed by Uzbekistan, at 3.97 percent, Cambodia, 1.65 percent, India, 1.4 percent, and Qatar, 1.36 percent.

While India is home to more enslaved people than any other country, the Walk Free Foundation report said it had made "significant progress" in measures to address the problem. Those included toughened criminal penalties for child prostitution and forced marriage, as well as improvements to protect victims.

The report also cited what it described as "significant progress" in antislavery actions by other governments since publication of the last report in 2014. The British government, for example, introduced the Modern Slavery Act last year, which can penalize violators with life imprisonment terms, and the United States amended a law to ban the importation of goods made with forced or child labor.

The countries with the lowest per capita rates of modern slavery - defined as 0.02 percent of the population or less, were: Luxembourg, New Zealand, Ireland, Norway, Denmark, Switzerland, Austria, Sweden, Belgium, Australia, Canada, Spain, Britain, France, Germany and the United States.

The Walk Free Foundation was founded in 2012 by Australian philanthropists, Andrew and Nicola Forrest, and developed what it described as the world's first all-encompassing global estimate of slavery with country-by-country data.

Source: The New York Times.