This is a figure for the whole of Iran. So it includes not just the Persian-majority areas, but also the minority-majority areas (Azeris, Kurds, Balochs, Arabs, Armenians, etc). It would not surprise me if the death toll in the minority-majority areas were higher, and hence they contributed a disproportionate percentage of the total, since security forces would likely find it easier to do that to people of a different ethnicity and/or religion (some of these minorities are predominantly Sunni, Christian, etc) than to people more like themselves.