Levene enrolled at Columbia University and in his spare time conducted biochemical research, publishing papers on the chemical structure of sugars. In 1896 he was appointed as an Associate in the Pathological Institute of the New York State Hospitals, but he had to take time off to recuperate from tuberculosis.
This graph shows the median age of the resident population of the United States from 1960 to 2015. In 2015, the median age of the United States population was approximately 37.7 years.
There are just over 40 million Americans age 65 and older, and they make up 13 percent of the population. By 2030, when all the baby boomers will have passed age 65, the over-65 crowd will reach 20 percent of the population. At that time the median age of Americans will increase to 39.6 years, up from 37.2 today and a significant increase from a little under 30 in the 1960s and '70s.