Year	gross (GPI)
1970	0.712830007076263
1971	0.718680024147034
1972	0.728489995002747
1973	0.736469984054565
1974	0.747179985046387
1975	0.751709997653961
1976	0.753549993038177
1977	0.76911997795105
1978	0.781539976596832
1979	0.786319971084595
1980	0.797940015792847
1981	0.80773001909256
1982	0.808839976787567
1983	0.807640016078949
1984	0.812539994716644
1985	0.815519988536835
1986	0.821039974689484
1987	0.832120001316071
1988	0.813570022583008
1989	0.840330004692078
1990	0.830569982528687
1991	0.837989985942841
1992	0.843370020389557
1993	0.842930018901825
1994	0.844709992408752
1995	0.839510023593903
1996	0.842589974403381
1997	0.841560006141663
1998	0.838599979877472
1999	0.847029983997345
2000	0.85113000869751
2001	0.858370006084442
2002	0.857649981975555
2003	0.865199983119965
2004	0.873070001602173
2005	0.882319986820221
2006	0.894320011138916
2007	0.903620004653931
2008	0.910730004310608
2009	0.918860018253326
2010	0.924730002880096
2011	0.922990024089813
2012	0.936619997024536
2013	0.943870007991791
2014	0.949919998645782
2015	0.956130027770996
2016	0.954039990901947
2017	0.956229984760284
2018	0.957350015640259
2019	0.957449972629547
2020	0.957690000534058