Year	gross (GPI)
2004	0.949779987335205
2005	0.973200023174286
2008	0.985069990158081
2009	0.972500026226044
2010	0.991867303848267
2011	1.0119491815567
2012	1.01935136318207
2013	1.0350114107132
2014	1.05624532699585
2015	1.05270636081696
2016	1.05684542655945
2017	1.06537890434265
2018	1.07727742195129
2019	1.08693611621857
2020	1.09422159194946