Transparency International has annually since 1996 released a global corruption index aim at representing the level of public-sector corruption. The results from the 2009 Global Corruption Index has recently been released.
New Zealand, Denmark, and Singepore received the highest score (least corrupt), while Somalia, Afghanistan, and Myanmar have most improvement potential.
Good scores reflect political stability, long-established conflict of interest regulations and solid, functioning public institutions. Furthermore, the results show that countries which are perceived to have the highest levels of public-sector corruption are also those plagued by long-standing conflicts, which have torn apart their governance infrastructure. (What is new in the 2009 Corruption Perceptions Index)
The corruption index is calculated based on results from survey questions posed to business leaders around the world (Transparency International Frequently Asked Questions)