Year	Percent
1991	35.149
1992	35.454
1993	36.334
1994	36.856
1995	36.137
1996	32.965
1997	32.301
1998	33.436
1999	32.513
2000	31.012
2001	31.329
2002	30.072
2003	27.171
2004	31.031
2005	35.967
2006	38.988
2007	42.463
2008	45.312
2009	49.343
2010	50.276
2011	50.16
2012	51.714
2013	54.641
2014	55.49
2015	55.805
2016	55.382
2017	55.786
2018	55.68
2019	55.746
2020	55.948
2021	56.091
2022	56.079