Year	gross (GPI)
1981	0.979070007801056
1986	0.988929986953735
1989	0.996270000934601
1990	1.01235997676849
1992	1.02922999858856
1999	1.01219999790192
2000	1.01432001590729
2001	0.995440006256104
2002	0.99712997674942
2003	1.00292003154755
2004	1.00265002250671
2005	0.995829999446869
2006	0.995980024337769
2007	0.996860027313232
2009	1.03050005435944
2010	0.994780004024506
2011	0.99905002117157
2012	0.994459986686707
2013	1.00051999092102
2014	1.00049996376038
2015	1.00497996807098
2016	0.994889974594116
2017	0.995329976081848
2018	0.996949970722198
2019	0.993589997291565
2020	0.998260021209717
2021	1.00077998638153