Of the total 4,78,600 prison inmates in the country, 3,15,409 or 65.90 per cent belong to the Scheduled Castes, Scheduled Tribes and the Other Backward Class categories, according to government data presented in Parliament on Wednesday. The prison statistics presented by Minister of State for Home Affairs G Kishan Reddy were based on a compilation of data by the National Crime Records Bureau (NCRB) updated till December 31, 2019.