Source: http://science.education.nih.gov/supplements/nih1/diseases/activities/activity5_measles-database.htm#5
The measles death rate in America had already dropped by about 99% between 1901 and 1968, when the measles vaccine was introduced.
I don’t know about the worldwide rates, but public sanitation and improvements in nutrition in America were responsible for the drop in measles deaths here.
I wouldn’t we surprised if someone in sub-saharan Africa did not have access to sewage treatment, clean water and the cod liver oil which was used to successfully manage measles before the vaccine appeared.