I can't find exact deets right now, but I think it is the Economist Intelligence Unit that does a global corruption survey by counting the industries from which billionaires in all the various countries gained their wealth. If too high a proportion of the billionaires in one country got their cash from mining, defence or construction, that country is sort of hosed because those are usually the most corrupt industries in any country.
You probably wouldn't want a construction industry billionaire to become PM or president of any major economy *ahem*.