Year	gross (GPI)
1971	0.641529977321625
1973	0.67535001039505
1974	0.66390997171402
1975	0.665840029716492
1976	0.653550028800964
1977	0.645410001277924
1978	0.655170023441315
1979	0.64749002456665
1980	0.660640001296997
1981	0.64206999540329
1982	0.648580014705658
1983	0.625989973545074
1984	0.620530009269714
1985	0.626330018043518
1987	0.697030007839203
1988	0.665549993515015
1989	0.664929986000061
1990	0.662519991397858
1995	0.725809991359711
1999	0.804239988327026
2000	0.816969990730286
2001	0.840919971466064
2002	0.849259972572327
2003	0.853489995002747
2004	0.837140023708344
2005	0.837930023670197
2006	0.851740002632141
2007	0.879859983921051
2008	0.888159990310669
2009	0.88401997089386
2011	0.901639997959137
2012	0.901090025901794
2013	0.912599980831146
2014	0.939769983291626
2015	0.949259996414185
2016	0.967719972133636
2017	0.973659992218018
2018	0.985480010509491
2019	0.998700022697449
2020	1.00419998168945