Year	gross (GPI)
1970	0.962369978427887
1971	0.9653599858284
1972	0.961470007896423
1973	0.967429995536804
1974	0.975160002708435
1975	0.984099984169006
1976	0.985679984092712
1977	0.983519971370697
1978	0.984889984130859
1979	0.998749971389771
1980	1.00124001502991
1981	1.0038800239563
1982	1.00156998634338
1983	1.00100994110107
1984	0.999419987201691
1985	0.989700019359589
1986	1.00344002246857
1987	1.00582003593445
1988	1.01031994819641
1989	1.01178002357483
1990	1.01627004146576
1991	1.01496005058289
1992	1.01354002952576
1993	1.01223003864288
1994	1.01014995574951
1995	1.00893998146057
1996	1.00585997104645
1997	1.00724995136261
1998	1.00694000720978
1999	1.00942003726959
2000	1.01113998889923
2001	1.00909996032715
2002	1.00902998447418
2003	1.01813995838165
2004	1.01688003540039
2005	1.01608002185822
2006	1.01776003837585
2007	1.02587997913361
2008	1.02646005153656
2009	1.0278400182724
2010	1.0215699672699
2011	1.0204199552536
2012	1.01868999004364
2013	1.01595997810364
2014	1.0161999464035
2015	1.01640999317169
2016	1.01423001289368
2017	1.0127899646759
2018	1.01470994949341
2019	1.01691997051239
2020	1.01687002182007