Japan's unified college entrance exams have been tainted by 65 irregularities — including two substitute test-takers — over the past decade, the exam's supervising body has revealed.

This resulted in the punishment of 67 people by invalidating test scores in all subjects, the National Center for University Entrance Examinations said Saturday.

Cases of misconduct were discovered each year from 2006 to 2015, the center said, noting that it had withheld the details until now.