Year	gross (GPI)
1971	0.742429971694946
1972	0.68911999464035
1973	0.708140015602112
1986	0.808870017528534
1987	0.770139992237091
1988	0.772580027580261
1989	0.782140016555786
1994	0.831679999828339
1995	0.815429985523224
1997	0.830429971218109
1998	0.842060029506683
1999	0.869140028953552
2000	0.877560019493103
2001	0.894980013370514
2002	0.902610003948212
2003	0.91117000579834
2004	0.920270025730133
2005	0.929120004177094
2006	0.933950006961823
2007	0.933130025863647
2008	0.937940001487732
2009	0.934880018234253
2010	0.943549990653992
2011	0.932052195072174
2012	0.92999929189682
2013	0.906803786754608
2014	0.944011270999908
2015	0.961631536483765
2016	0.973157167434692
2017	0.974083721637726
2018	0.97404807806015
2019	0.969961822032928
2020	0.96986997127533
2021	0.981125771999359