Last month I tried to estimate how much of Sri Lankan youth go overseas for studies. I found this Island article which puts a number on that estimation:

Around 7,000 students go abroad for higher education annually but the Higher Education Ministry does not keep records or register students going abroad for higher studies privately, Ministry Secretary Mrs. P. B. G. Abeyratne said.

However, the Controller of Immigration and Emigration P. B. Abeykoon said there may be more than 7,000 who go abroad annually for studies but around 20,000 passports are issued purportedly for those leaving the country for higher education.

Higher Education Ministry sources attributed this large exodus of students to the inability of universities to admit all those who qualify at the AL examination. Parents who could afford to send their children abroad do so, source added. "This is a feature of the global scenario of this era."

Though university education is free, it can accommodate only a limited number of students. Currently, there are only 16 state universities and only about 16,000 students are admitted. [link]

7,000 seems like a conservative estimate, especially if the number of student visas issued are around 20,000. But even 7,000 per year is a big number, given that the state Universities can accommodate only around 16,000. There is absolutely no case for free higher education, more on that soon.