Year	Percent
1991	69.503
1992	68.362
1993	65.657
1994	63.292
1995	60.795
1996	58.892
1997	58.063
1998	57.619
1999	57.102
2000	56.385
2001	55.586
2002	54.493
2003	52.659
2004	50.189
2005	48.454
2006	46.657
2007	44.796
2008	42.61
2009	41.654
2010	40.191
2011	38.791
2012	37.905
2013	37.334
2014	36.749
2015	36.545
2016	36.175
2017	36.151
2018	36.08
2019	36.014
2020	35.95
2021	35.889
2022	35.829