Year	gross (GPI)
1970	1.04164004325867
1971	1.03427994251251
1972	1.01709997653961
1973	1.00567996501923
1974	0.995469987392426
1975	0.985339999198914
1976	0.97842001914978
1977	0.959179997444153
1978	0.948859989643097
1979	0.935739994049072
1980	0.929229974746704
1981	0.918529987335205
1982	0.911099970340729
1983	0.903620004653931
1984	0.895929992198944
1985	0.878080010414124
1986	0.874459981918335
1987	0.930989980697632
1988	0.891269981861115
1989	0.872510015964508
1990	0.884400010108948
1991	0.885049998760223
1992	0.889119982719421
1993	0.896340012550354
1994	0.901189982891083
1995	0.903859972953796
1996	0.90777999162674
1997	0.91430002450943
1998	0.913659989833832
1999	0.937110006809235
2000	0.938629984855652
2001	0.931749999523163
2002	0.921140015125275
2003	0.911130011081696
2004	0.922490000724792
2005	0.934759974479675
2006	0.961650013923645
2007	0.980430006980896
2008	0.999859988689423
2009	0.989090025424957
2010	0.971719980239868
2011	0.947120010852814
2012	0.933409988880157
2013	0.930559992790222
2014	0.919780015945435
2015	0.914910018444061
2016	0.922640025615692
2017	0.919380009174347
2018	0.915180027484894
2019	0.909389972686768