Proekt’s report highlights discrepancies between official data from the Rosstat federal statistics agency and data compiled by countries where Russians emigrate to. Rosstat estimates 377,000 Russians left the country in 2017, the latest period for which figures are available and a six-year record.

At least six times more Russians are leaving the country than officially estimated, a comprehensive study conducted by the Proekt news outlet said on Wednesday.

“The U.S. Department of Homeland Security counted six times more Russians arriving in 2017 than Rosstat recorded [leaving],” Proekt said. “Six times more people left Russia for 24 OECD countries, where foreign data is available, for 2016.”

OECD, the Organization of Economic Cooperation and Development, groups 34 of the world’s leading economies.

Meanwhile, the UN ranks Russia as having the third largest number of people living outside its borders after India and Mexico — 10.6 million.

Proekt said an increasing number of highly-educated young Russians from the regions are leaving the country in search of better economic opportunities.

Official data from Rosstat underestimates the real number of Russian emigres because it only counts those who have officially canceled their registration in Russia — which most emigres don’t do.

The Civil Initiatives Committee, formed by Audit Chamber chairman Alexander Kudrin, previously estimated that in 2014, the real number of Russians emigrating abroad was between three to four times higher than Rosstat’s data.

That report also shed light on Russia’s brain drain, with both Russian and foreign data indicating the high level of human capital leaving the country.

A 2018 state-funded survey said that one in 10 Russians, including almost one-third of those aged 18 to 24, want to emigrate. A quarter of respondents named a relative or acquaintance who had moved out of Russia in recent years.

Rosstat’s 2018 migration data is expected in July.