*“no more than 50% of patents are renewed past 10 years” (Scotchmer 1999)
:: ```Scotchmer, S. (1999). On the optimality of the patent renewal system. The RAND Journal of Economics, pp. 181-96.``` [http://www.jstor.org/stable/2556076?seq=1#page_scan_tab_contents Link]
*“less than forty percent of patentees pay all three maintenance fees"