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.
The U.S. is growing, and the world is growing faster. The U.S. entered 2016 with an estimated population of 322,762,018 according to an end-of-year estimate from the U.S. Census Bureau, meaning that we added more than 2.4 million people to the population over the course of the year.