Year	Percent
1991	31.568
1992	32.278
1993	32.239
1994	32.707
1995	33.134
1996	33.555
1997	34.597
1998	35.678
1999	37.058
2000	37.846
2001	38.082
2002	38.541
2003	38.691
2004	38.661
2005	39.311
2006	43.654
2007	45.066
2008	46.112
2009	46.984
2010	48.51
2011	49.496
2012	48.753
2013	47.111
2014	48.244
2015	50.877
2016	52.177
2017	52.818
2018	53.939
2019	55.574
2020	56.88
2021	57.956
2022	58.971