Year	gross (GPI)
1971	0.99151998758316
1972	0.990899980068207
1973	0.996810019016266
1974	1.00863003730774
1975	1.01101994514465
1976	1.01529002189636
1977	1.01810002326965
1978	1.02011001110077
1979	1.02068996429443
1980	1.02514004707336
1981	1.02143001556396
1982	1.0129599571228
1983	1.00093996524811
1984	1.00074994564056
1985	1.00139999389648
1986	1.00077998638153
1987	1.00013995170593
1988	1.00295996665955
1989	1.01758003234863
1990	1.00866997241974
1991	1.00487995147705
1992	0.99958997964859
1993	0.993789970874786
1994	0.995029985904694
1995	1.00090003013611
1996	1.00159001350403
1998	0.994109988212585
1999	1.01727998256683
2000	1.01946997642517
2005	0.978020012378693
2006	0.979920029640198
2007	0.978120028972626
2008	0.976610004901886
2009	0.976859986782074
2010	0.976580023765564
2011	0.979749977588654
2012	0.997669994831085
2013	1.00230002403259
2014	1.00567996501923
2015	1.00885999202728
2016	1.01515996456146
2017	1.01303994655609
2018	1.01071000099182
2019	1.00835001468658
2020	1.01105999946594