If that figure is suggesting that 42.77 per cent of those on death row are black then there is a serious problem. Unless 42% of the population are black that suggests the death sentence is being disproportionately applied to black americans
Or are those figures indicative of something else? more info please
I followed the link you provided on your post . Wasnt able to find those figures but did find a very interesting article
Towards Death Penalty Reforms