South Africa has a pretty developed life insurance industry. You could try getting the mortality tables (different from morbidity which is disablement, not death) somewhere.
Maybe google some combos with actuary, life insurance, mortality tables and of course the country's stat dept may have it. There should be tables based on different years too.
Just don't forget that it's hard to isolate mortality influences (say just because of Arpartheid) across time as there are multiple factors that would affect mortality - improving health services, etc.
There may be papers that discuss mortality trends in South Africa, which may be closer to what you need.