Year	gross (GPI)
1971	0.763520002365112
1972	0.809149980545044
1973	0.833000004291534
1974	0.875800013542175
1975	0.94989001750946
1976	0.97121000289917
1977	1.00345003604889
1978	1.02448999881744
1979	1.16838002204895
1980	0.729210019111633
1986	1.15005004405975
1988	1.13858997821808
1990	1.00514996051788
1991	1.16058003902435
1993	1.13952994346619
1994	1.08847999572754
1995	1.07770001888275
1996	1.09001994132996
1998	1.07776999473572
1999	1.08177995681763
2000	1.06666994094849
2001	1.05707001686096
2002	1.04972994327545
2003	1.09121000766754
2004	1.10611999034882
2005	1.09976994991302
2006	1.08884000778198
2007	1.07425999641418
2008	1.05815994739532
2009	1.04324996471405
2010	1.02803003787994
2011	1.01850998401642
2012	0.998839974403381
2013	0.984769999980927
2014	0.976189970970154
2015	0.969500005245209
2016	0.973339974880219
2017	0.980300009250641
2018	0.995779991149902
2019	1.00462996959686
2020	1.0045599937439