A) Kaplan-Meier survival curves corresponding to individuals who died in the 11-12 year intervals of 1968-1980 (n=4 gray solid line), 1981-1993 (n=37, gray dashed line), 1994-2005 (n=163, black solid line), 2006-2018 (n=133, black dashed line). B) Kaplan-Meier survival curves corresponding to 256 individuals with NPC who have died in the last 20 years. Each curve represents a 5-year interval. Intervals are 1998-2002 (n=70, gray solid line), 2003-2007 (n=70, gray dashed line), 2008-2012 (n=54, black solid line) and 2013-2018 (n=62, black dashed line).