Transparency International (TI) has issued the 2012 edition of its corruption index. The least corrupt countries in the world according to this index are Denmark, Finland and New Zealand. The most corrupt countries are Afganistan and North Corea. Spain is in position 30 in the ranking, tied with Botswana. Portugal and Italy are even below Spain.
TI says that "A growing outcry over corrupt governments forced several leaders from
office last year, but as the dust has cleared it has become apparent
that the levels of bribery, abuse of power and secret dealings are still
very high in many countries. Transparency International’s 2012 Index shows that corruption continues to ravage societies around the world.
Two thirds of the 176 countries ranked in the 2012 index score below
50, on a scale from 0 (perceived to be highly corrupt) to 100 (perceived
to be very clean), showing that public institutions need to be more
transparent, and powerful officials more accountable."
TI's index is not perfect. It does not take into account some forms of corruption: for example, Chile looks very decent, but no account is made of the fact that one of the richest (perhaps THE richest) man in the country is the president, which is only the tip of the iceberg of a country where the business oligarchy has enormous political and social power (isn't that corruption? If it is not, then they don't need to become corrupt). Another example is the presence of politically connected agents in the board of directors or other positions in large firms.
In any case, it is a very decent effort. Corruption is one of the most serious challenges facing our societies, and as a brief reflection on the top and bottom countries suggests, it is very strongly correlated with social welfare.