When it comes to studying abroad, the U.S. is no longer THE place to go.

A new global migration report by the Organization for Economic Cooperation shows American universities are losing their supreme position in the global education system.

In 2000, nearly one in four students looking for education abroad picked a college in the U.S.

In 2012 -- the latest year for which data is available -- it was just 16%.

Although the U.S. still attracts the highest proportion of foreign students, other countries are becoming increasingly popular, biting into the U.S. market share.

All other English-speaking developed countries and Spain have increased their share of foreign students.

The United Kingdom has seen the biggest growth in its share, trailing closely behind the U.S. with 12.6%. This is good news for British universities, as foreign students pay up to three times more in tuition than students from Britain and the EU.

South Korea has also increased its share dramatically, from less then 0.2% in 2000 to 1.3% in 2012.

Related: America's brain drain dilemma

More than 4.5 million students enrolled outside their own country in 2012, with three-quarters of them studying in developed countries. Over half came from Asia, with China now representing 22% of all international students, followed by India and Korea.

The OECD praises countries that welcome international students, saying they boost local economies, since they speak the language and employers understand their qualifications.