Several years ago; the OECD started to compile data based on population censuses of OECD countries for the 2000 census round.

Since then; another round was added to the first one. And the OECD and the World Bank have joined their efforts in a project aimed at extending the coverage of the Database on Immigrants in OECD Countries (DIOC) to non-OECD destination countries (DIOC-E or DIOC extended). This data collection made it possible to calculate e‌migration rates by skill level.

The datasets include information on demographic characteristics (age and gender); duration of stay; labour market outcomes (labour market status; occupations; sectors of activity); fields of study; educational attainment and the place of birth.

DIOC contains information for the 34 OECD countries (destinations) and more than 200 countries of origin in the years 2000; 2005 and 2010. DIOC-E contains information for 100 destination countries and more than 200 countries of origin in the years 2000 and 2010.