Original sentence: At the time of the last Soviet census in 1989, it had a population of about 500,000, of whom 48 percent were Georgians (principally Mingrels) and only 17 percent of whom were Abkhazians
Edited sentence: At the time of the last Soviet census in 1989, it had a population of about 500,000, of whom 48 percent were Georgians (principally from Mingrelia) and only 17 percent of whom were native Abkhazians