Year	gross (GPI)
1976	1.06984996795654
1981	0.990230023860931
1982	0.996749997138977
1983	0.994369983673096
1984	0.996800005435944
1985	0.9998499751091
1986	1.00069999694824
1987	0.983609974384308
1988	1.01374995708466
1989	1.01347994804382
1990	0.982400000095367
1991	0.993770003318787
1992	0.997789978981018
1993	0.998740017414093
1994	1.02447998523712
1995	0.994310021400452
1996	0.982370018959045
1997	1.00152003765106
1998	0.99524998664856
1999	1.0020899772644
2001	1.00199997425079
2002	0.992160022258759
2003	0.988359987735748
2004	0.986710011959076
2005	0.989719986915588
2006	0.987290024757385
2007	0.987600028514862
2008	0.990239977836609
2009	0.988849997520447
2014	0.979579985141754
2015	0.970080018043518
2016	0.966678142547607
2017	0.964394211769104
2018	0.962437927722931
2019	0.970158874988556
2020	0.976088404655457
2021	0.976957738399506