Year	gross (GPI)
1970	0.769190013408661
1971	1.06787002086639
1972	1.03970003128052
1974	0.815199971199036
1975	2.44944000244141
1976	3.09193992614746
1977	0.886770009994507
1978	0.872609972953796
1979	0.89504998922348
1980	0.85970002412796
1981	0.881900012493134
1982	0.887319982051849
1985	0.907549977302551
1991	0.945370018482208
1995	0.954339981079102
1998	0.962750017642975
1999	0.956520020961761
2000	0.947130024433136
2001	0.945010006427765
2002	0.942879974842072
2003	0.95168000459671
2004	0.988839983940125
2005	0.986020028591156
2006	1.00890004634857
2007	1.02276003360748
2008	1.03716003894806
2009	1.0267299413681
2010	1.02616000175476
2011	1.00601994991302
2012	0.974049985408783
2013	0.982159972190857
2014	0.985530018806458
2015	0.99576997756958
2016	0.974539995193481
2017	0.959659993648529
2018	0.948450028896332
2019	0.941630005836487
2020	0.934409976005554
2021	0.949090003967285