Year	gross (GPI)
1970	0.958530008792877
1971	0.95907998085022
1972	0.961130023002625
1973	0.968129992485046
1974	0.964380025863647
1975	0.9791100025177
1976	0.982710003852844
1977	0.987569987773895
1978	0.992699980735779
1979	0.994470000267029
1980	1.00116002559662
1981	1.01362001895905
1982	1.00651001930237
1983	1.01425004005432
1984	1.01284003257751
1985	1.01468002796173
1986	1.01827001571655
1987	1.01924002170563
1988	1.01800000667572
1989	1.01203000545502
1990	1.01113998889923
1991	1.01549994945526
1992	1.01988995075226
1993	1.01383996009827
1994	1.00757002830505
1995	1.01031005382538
1996	1.01296997070313
1997	1.00949001312256
1998	1.01118004322052
1999	1.01177000999451
2000	1.00876998901367
2001	1.00977003574371
2002	1.00750994682312
2003	1.00863003730774
2004	1.00967001914978
2005	1.00717997550964
2006	1.00488996505737
2007	1.00424003601074
2008	1.00393998622894
2009	0.998260021209717
2010	0.995410025119781
2011	0.993430018424988
2012	0.991310000419617
2013	1.00265002250671
2014	1.00317001342773
2015	1.00206995010376
2016	1.00179004669189
2017	0.998849987983704
2018	1.0001699924469
2019	1.00082004070282
2020	1.0037100315094