Year	gross (GPI)
1970	0.589709997177124
1971	0.588989973068237
1972	0.596719980239868
1973	0.60588002204895
1974	0.613020002841949
1975	0.622500002384186
1976	0.635680019855499
1977	0.649200022220612
1978	0.660250008106232
1979	0.681439995765686
1980	0.694429993629456
1981	0.707840025424957
1982	0.719060003757477
1983	0.730859994888306
1984	0.743920028209686
1985	0.756410002708435
1986	0.766709983348846
1987	0.774479985237122
1988	0.779100000858307
1989	0.791689991950989
1990	0.804080009460449
1991	0.814800024032593
1992	0.828719973564148
1993	0.83840000629425
1994	0.843119978904724
1995	0.857060015201569
1996	0.847259998321533
1997	0.86913001537323
1998	0.878700017929077
1999	0.889410018920898
2000	0.898249983787537
2001	0.906189978122711
2002	0.91253000497818
2003	0.919269979000092
2004	0.925130009651184
2005	0.930280029773712
2006	0.93436998128891
2007	0.942300021648407
2008	0.939989984035492
2009	0.938970029354095
2010	0.94063001871109
2011	0.939769983291626
2012	0.946200013160706
2013	0.951210021972656
2014	0.957459986209869
2015	0.961989998817444
2016	0.961000025272369
2017	0.961009979248047
2018	0.965489983558655
2019	0.967220008373261
2020	0.971140027046204