Denmark's Queen Margrethe II and Prince Consort Henrik (L) leave the Notre-Dame Cathedral after the religious wedding service of Luxembourg's Hereditary Grand Duke Guillaume and his wife Princess Stephanie in Luxembourg October 20, 2012. REUTERS/Vincent Kessler Denmark, New Zealand, Finland, and Sweden are the four least corrupt countries in the world, according to Transparency International's 2013 Corruption Perceptions Index (CPI).

The U.S. is listed as the 19th least corrupt country.

Somalia, North Korea, and Afghanistan are the most corrupt.

The CPI ranks countries and territories based on how corrupt their administrative and political institutions are perceived to be on a scale from 0 (highly corrupt) and a 100 (very clean).

Denmark and New Zealand both scored a 91 while Finland and Sweden both scored 89.

Over the last 20 years, New Zealand has developed into a free market economy in which welfare is provided mostly on the basis of need.

The other three countries follow the general Nordic welfare model, which supports a "universalist" welfare state aimed at enhancing individual autonomy and promoting social mobility by maximizing labor force participation, promoting gender equality, providing extensive benefits, and redistributing wealth.

Denmark goes as far as involving the private sector in welfare services and providing choice for users.

This graphic gives an indication of the spectrum of global corruption, which is most concentrated in East Europe & Central Asia as well as Sub-Saharan Africa.