"The share of new entrepreneurs ages 55-64 grew from 14.3% to 23.4% from 1996 to 2012." The oldest age group (ages 55-64) experienced a rising share of all new entrepreneurs, mainly because it represents an increasing share of the population," according to the 2013 Kauffman Index of Entrepreneurial Activity.
Fairlee, R. W. (2013). Kauffman index of entrepreneurial activity 1996-2012. Kansas City, MO: Kauffman Foundation. Retrieved from www.kauffman.org.