Year	gross (GPI)
1981	0.756139993667603
1986	0.818849980831146
1991	0.969200015068054
1992	0.953570008277893
1993	0.949419975280762
1994	0.96153998374939
1995	0.936869978904724
1996	0.988910019397736
1997	0.987049996852875
1999	1.00931000709534
2000	1.02014005184174
2001	1.03804004192352
2002	1.03070998191833
2003	1.03231000900269
2004	1.04896998405457
2005	1.03863000869751
2006	1.08153998851776
2008	1.03157997131348
2013	1.02667999267578
2014	1.03322005271912
2015	1.02771997451782
2016	1.01774001121521
2017	1.01057004928589
2018	1.01428997516632
2019	1.00812995433807
2020	1.00990998744965
2021	1.00392997264862