Year	gross (GPI)
1971	1.02191996574402
1972	1.12082004547119
1973	1.15814995765686
1974	1.20490002632141
1975	1.25662004947662
1976	1.27419996261597
1977	1.29841995239258
1978	1.41884994506836
1979	1.29489994049072
1980	1.27562999725342
1981	1.24399995803833
1982	1.17232000827789
1983	1.14727997779846
1984	1.1662700176239
1985	1.17674005031586
1986	1.20443999767303
1987	1.23242998123169
1988	1.24221003055573
1989	1.19371998310089
1990	1.14193999767303
1991	1.1015499830246
1992	1.16717004776001
1993	1.28600001335144
1994	1.32915997505188
1995	1.37228000164032
1996	1.40780997276306
1997	1.38803994655609
1998	1.37723004817963
1999	1.3388899564743
2000	1.29034996032715
2001	1.26348996162415
2002	1.19484996795654
2003	1.15926003456116
2004	1.15160000324249
2005	1.13943004608154
2006	1.18439996242523
2007	1.19049000740051
2008	1.24255001544952
2009	1.24770998954773
2010	1.24383997917175
2011	1.23137998580933
2012	1.21722996234894
2013	1.21298003196716
2014	1.20615994930267
2015	1.21711003780365
2016	1.19848001003265
2017	1.19290995597839
2018	1.18986999988556
2019	1.19813001155853
2020	1.19525003433228
2021	1.20981001853943