Complex sentence: In the years between 1938 and the approval of the Salk vaccine in 1955, the foundation spent $233 million on polio patient care, leading to more than 80 percent of polio patients in the U.S. receiving significant foundation aid.
Split into simpler sentences: In the years between 1938 and the approval of the Salk vaccine in 1955, the foundation spent $233 million on polio patient care. This policy resulted in more than 80 percent of polio patients in the U.S. receiving significant foundation aid.