Year	gross (GPI)
1975	0.351240009069443
1976	0.374779999256134
1977	0.38034000992775
1978	0.387360006570816
1979	0.396649986505508
1981	0.444409996271133
1982	0.495779991149902
1986	0.529579997062683
1990	0.573870003223419
1992	0.586960017681122
1994	0.611220002174377
1997	0.63646000623703
2004	0.785090029239655
2007	0.793950021266937
2010	0.825957715511322
2011	0.821382164955139
2012	0.830791175365448
2013	0.839315414428711
2014	0.854593932628632
2016	0.885045170783997
2017	0.901470303535461