Year	gross (GPI)
1970	0.953379988670349
1971	0.957840025424957
1972	0.958890020847321
1973	0.956870019435883
1974	0.959020018577576
1975	0.953429996967316
1976	0.964129984378815
1977	0.961409986019135
1978	0.960650026798248
1979	0.959949970245361
1980	0.960690021514893
1981	0.960110008716583
1982	0.961210012435913
1983	0.954770028591156
1984	0.948260009288788
1985	0.951740026473999
1986	0.952889978885651
1987	0.952199995517731
1988	0.959200024604797
1989	0.966740012168884
1990	0.962909996509552
1999	0.966069996356964
2000	0.967079997062683
2001	0.966780006885529
2002	0.965550005435944
2003	0.965149998664856
2004	0.968020021915436
2005	0.965439975261688
2006	0.967610001564026
2007	0.967859983444214
2008	0.96508002281189
2009	0.965219974517822
2010	0.963800013065338
2011	0.970640003681183
2012	0.970430016517639
2013	0.972970008850098
2014	0.976509988307953
2015	0.97545999288559
2016	0.984210014343262
2017	0.978829979896545
2018	0.986315011978149
2019	0.984726011753082
2020	0.989149987697601
2021	0.989219427108765