I really like this graphic illustrating the reduction in incidence of VPDs (vaccine preventable diseases) in the last 110 years.
I know some of you will object to this reduction being linked to vaccines, and I agree from 1900s to now it's not only the introduction of more common vaccination which has changed, however you're probably not surprised that I believe there is a link. And I'll jump the gun and post the below which at least for Polio to me demonstrates a clear link.
This shows the rates of polio (and polio deaths) per 100,000 people from 1932 until what looks like 1992. IPV = inactivated polio vaccine (arrow indicates when introduced), OPV = oral polio vaccine (similar).
I took this last one from The Polio Survivors Network, here: http://www.poliosurvivorsnetwork.org.uk/archive/lincolnshire/library/gawne/ppspandcm.htm
Would be nice to collect as up-to-date as possible versions of these graphs for other VPDs. Does anyone know of a link for that?