Year	gross (GPI)
1970	0.990679979324341
1971	0.991349995136261
1972	0.991550028324127
1973	0.99549001455307
1974	0.990140020847321
1975	0.989849984645844
1976	0.994029998779297
1977	0.99074000120163
1978	0.992820024490356
1979	0.993340015411377
1980	0.995589971542358
1981	0.996309995651245
1982	0.993560016155243
1983	0.98895001411438
1984	0.991320013999939
1985	0.992900013923645
1986	0.991810023784637
1987	0.988210022449493
1988	0.98701000213623
1989	0.987410008907318
1990	0.988960027694702
1991	0.986100018024445
1992	0.98675000667572
1993	0.98676997423172
1994	0.989449977874756
1995	0.988600015640259
1996	0.987919986248016
1997	0.99370002746582
1998	0.999549984931946
1999	1.00088000297546
2000	0.988870024681091
2001	0.993659973144531
2002	0.9964399933815
2003	0.994570016860962
2004	0.992370009422302
2005	0.99099999666214
2006	0.997169971466064
2007	0.996290028095245
2008	0.994700014591217
2009	0.996060013771057
2010	0.996640026569366
2011	0.996540009975433
2012	0.997030019760132
2013	0.995890021324158
2014	0.997300028800964
2015	1.00106000900269
2016	0.998820006847382
2017	0.996680021286011
2018	0.998809993267059
2019	1.00287997722626
2020	0.999450027942657