Year	gross (GPI)
1970	0.972850024700165
1971	0.97367000579834
1972	0.984120011329651
1973	0.984220027923584
1974	0.986459970474243
1975	0.981130003929138
1976	0.978839993476868
1977	0.979420006275177
1978	0.980599999427795
1979	0.982110023498535
1980	0.983039975166321
1981	0.982460021972656
1982	0.978569984436035
1983	0.981079995632172
1984	0.981519997119904
1985	0.985840022563934
1986	0.978680014610291
1987	0.980570018291473
1988	0.981500029563904
1989	0.98158997297287
1990	0.981149971485138
1991	0.976339995861053
1992	0.976170003414154
1993	0.972320020198822
1994	0.96900999546051
1995	0.965290009975433
1996	0.965129971504211
1997	0.962050020694733
1998	0.95932000875473
1999	0.961409986019135
2000	0.96017998456955
2001	0.961579978466034
2002	0.958580017089844
2003	0.962029993534088
2004	0.962779998779297
2005	0.964200019836426
2006	0.967559993267059
2007	0.968180000782013
2008	0.972100019454956
2009	0.973389983177185
2010	0.973619997501373
2011	0.972410023212433
2012	0.977069973945618
2013	0.977460026741028
2014	0.978229999542236
2015	0.983780026435852
2016	0.981379985809326
2017	0.981920003890991
2018	0.983049988746643
2019	0.98769998550415
2020	0.989579975605011