Nations do not necessarily need wealth to gain health. For example, Sri Lanka had a maternal mortality rate of 2% in the 1930s, higher than any nation today. It reduced it to 0.5–0.6% in the 1950s and to 0.6% today while spending less each year on maternal health because it learned what worked and what did not. Knowledge on the cost effectiveness of healthcare interventions can be elusive and educational measures have been made to disseminate what works, such as the Copenhagen Consensus. Cheap water filters and promoting hand washing are some of the most cost effective health interventions and can cut deaths from diarrhea and pneumonia.