Year	gross (GPI)
1970	0.471130013465881
1971	0.471599996089935
1972	0.479310005903244
1973	0.497370004653931
1974	0.492980003356934
1975	0.490119993686676
1976	0.485570013523102
1977	0.481610000133514
1978	0.504010021686554
1979	0.499190002679825
1980	0.486510008573532
1981	0.508910000324249
1982	0.529950022697449
1983	0.453990012407303
1984	0.412979990243912
1985	0.514720022678375
1986	0.628080010414124
1987	0.666899979114532
1988	0.661719977855682
1989	0.662289977073669
1990	0.656419992446899
1991	0.668579995632172
1992	0.676940023899078
1993	0.686529994010925
1994	0.694859981536865
1995	0.701910018920898
1996	0.716669976711273
1997	0.728470027446747
1998	0.731649994850159
1999	0.748600006103516
2000	0.728399991989136
2001	0.730310022830963
2002	0.688149988651276
2003	0.714860022068024
2004	0.726480007171631
2005	0.744790017604828
2006	0.740819990634918
2007	0.730019986629486
2008	0.761389970779419
2009	0.784049987792969
2010	0.798259973526001
2011	0.796480000019073
2012	0.831740021705627
2013	0.843529999256134
2014	0.836099982261658
2015	0.854480028152466
2016	0.854900002479553
2017	0.875829994678497
2018	0.893999993801117
2019	0.901859998703003