Year	gross (GPI)
1970	0.728910028934479
1971	0.729300022125244
1972	0.729889988899231
1973	0.730769991874695
1974	0.738120019435883
1975	0.743629992008209
1976	0.742799997329712
1977	0.745119988918304
1978	0.757189989089966
1979	0.768920004367828
1980	0.760209977626801
1981	0.751070022583008
1982	0.747560024261475
1983	0.760129988193512
1984	0.750630021095276
1985	0.74330997467041
1986	0.768199980258942
1987	0.779860019683838
1988	0.786029994487762
1989	0.794290006160736
1990	0.798070013523102
1991	0.804700016975403
1992	0.812770009040833
1993	0.818549990653992
1994	0.834930002689362
1995	0.845340013504028
1996	0.854189991950989
1997	0.865220010280609
1998	0.880770027637482
1999	0.894150018692017
2000	0.899179995059967
2001	0.902140021324158
2002	0.908309996128082
2003	0.924229979515076
2004	0.925809979438782
2005	0.934509992599487
2006	0.939909994602203
2007	0.946850001811981
2008	0.955070018768311
2009	0.966870009899139
2010	0.961380004882813
2011	0.965240001678467
2012	0.968739986419678
2013	0.981459975242615
2014	0.986419975757599
2015	0.986320018768311
2016	0.98853999376297
2017	0.987730026245117
2018	0.990790009498596
2019	0.991989970207214
2020	0.986760020256042