Year	Percent
1991	77.118
1992	77.317
1993	77.247
1994	77.335
1995	76.744
1996	76.458
1997	76.326
1998	76.259
1999	76.373
2000	75.63
2001	74.961
2002	73.839
2003	72.489
2004	70.812
2005	69.202
2006	67.367
2007	65.821
2008	63.516
2009	61.509
2010	59.49
2011	57.757
2012	56.003
2013	54.477
2014	52.68
2015	50.209
2016	49.765
2017	48.296
2018	46.562
2019	44.956
2020	43.406
2021	41.948
2022	40.848