The Corruption Perceptions Index is based on expert opinions of public sector corruption. Countries' scores can be helped by open government where the public can hold leaders to account, while a poor score is a sign of prevalent bribery, lack of punishment for corruption and public
institutions that don't respond to citizens' needs, the anti-corruption organization said.
With that in mind, the countries perceived as the most corrupt and the worst performers on the index in 2015 were North Korea and Somalia, each scoring 8 on the index.
Transparency International said that in addition to conflict and war, "poor governance, weak public institutions like police and the judiciary, and a lack of independence in the media characterize the lowest ranked countries."
In contrast, European nation Denmark is seen as the least corrupt country out of the 168 indexed, retaining the top spot for a second year in a row with a score of 91. Fellow Scandinavian countries Finland and Sweden came a close second and third place, respectively.
"Top performers share key characteristics: high levels of press freedom; access to budget information so the public knows where money comes from and how it is spent; high levels of integrity among people in power; and judiciaries that don't differentiate between rich and poor, and that are truly independent from other parts of government."
European countries dominated the top ten places in the index, although New Zealand was in fourth place and Singapore and Canada edged into the top ten.
While several countries improved their standing in the index, including Greece, Senegal and the U.K. (ranking jointly with Luxembourg in 10th place with its score rising to 81 on the index in 2015, from 78 in the previous year) others showed declines.
Emerging market Brazil was the biggest decliner in the index, falling 5 points and dropping 7 positions to a rank of 76. The result could be attributed to the unfolding Petrobras scandal which brought people onto the streets in 2015.