What is corruption perception index (CPI) ?

Corruption Perception Index (CPI)
It is an index which ranks the countries by their perceived levels of public sector corruption according to experts and business people.
Since 1996, it is being released by Berlin based Corruption watchdog named Transparency International.
CPI generally defines Corruption as the misuse of public power for private benefit.

Methodology
The index has been complied by using World Bank data, the World Economic Forum and other institutions.
The corruption perception index is measured with a different methodology year to year, making yearly comparisons difficult.
Because of this, it cannot be used as a tool for measuring the implications of new policies.
Scaling
It uses a scale of 0 to 100, where 0 is highly corrupt and 100 is very clean.
This year, the index found that more than two-thirds of countries score below 50, with an average score of 43.