Corruption perceptions index during each prime minister's tenure

Every prime minister since 1991, ranked by how the corruption perceptions index changed from their first day in office. Politare shows what happened during a tenure; it does not claim the office-holder caused it.

#	Prime minister	In office	Total	Per year	Chart
1	N Prayut Chan-o-cha	22 May 2014 – 9 Jun 2019	+1.0 points 2013 → 2018	+0.2 points/yr
2	Prayut Chan-o-cha	9 Jun 2019 – 22 Aug 2023	−1.0 points 2018 → 2023	−0.2 points/yr

Sorted by total, highest first. Every row is indexed to the last count complete before the first day in office ("from" marks a start that had to move because that count had no data, or because the period cut it); Levels are per cent changes, rates are differences in points; "per year" compounds levels and divides rates. Tenures with under 12 months, or under three observations, are left out. points, 0 to 100, higher is cleaner · Transparency International, Corruption Perceptions Index (CPI score): perceived public-sector corruption as business people and country experts rate it, comparable from 2012, the score as TI publishes it with its confidence interval · Thailand data · as of Aug 2026.