Short answers, pulled from the story.
Transparency International published its first Corruption Perceptions Index in 1995. Johann Graf Lambsdorff of the University of Passau commissioned the index for the organization to score countries by their perceived levels of public sector corruption.
Since 2012, the Corruption Perceptions Index has used a scale from one hundred down to zero. A score of one hundred means very clean governance while zero indicates high corruption.
One study calculated that GDP growth rises by 1.7 percent for every single unit increase in a country's score. Research papers published in 2007 examined economic consequences tied to these perception scores and found this correlation.
The original creator Johann Graf Lambsdorff withdrew from work on the index in 2009 stating he was no longer available. Political scientist Dan Hough identified three major flaws in how the Index functions today including elite bias.
A report titled Exporting Corruption 2022 assessed enforcement of the OECD Anti-Bribery Convention across forty-three signatories. It found a significant decline in foreign bribery enforcement globally with only two out of forty-seven countries now falling into the active enforcement category.