Given the task definition and input, reply with output. Answer the question from the given passage. Your answer should be directly extracted from the passage, and it should be a single entity, name, or number, not a sentence.

Passage: Kenya ranks low on Transparency International's Corruption Perception Index (CPI), a metric which attempts to gauge the prevalence of public sector corruption in various countries. In 2012, the nation placed 139th out of 176 total countries in the CPI, with a score of 27/100. However, there are several rather significant developments with regards to curbing corruption from the Kenyan government, for instance, the establishment of a new and independent Ethics and Anti-Corruption Commission (EACC). Question: What does the CPI scale measure?
public sector corruption