Year	gross (GPI)
1971	0.78004002571106
1974	0.808319985866547
1993	0.937820017337799
1994	0.961040019989014
2000	0.825779974460602
2001	0.968590021133423
2002	0.951910018920898
2003	0.985490024089813
2005	0.967100024223328
2008	0.964219987392426
2009	0.973200023174286
2010	0.987209975719452
2011	0.996699988842011
2012	0.994809985160828
2015	0.994090020656586