Year	Percent
1991	45.122
1992	45.066
1993	44.334
1994	44.766
1995	44.41
1996	44.291
1997	44.651
1998	45.648
1999	47.007
2000	47.461
2001	47.863
2002	48.771
2003	49.509
2004	51.101
2005	51.745
2006	52.702
2007	43.88
2008	36.341
2009	31.365
2010	28.928
2011	28.05
2012	27.737
2013	27.832
2014	28.205
2015	28.079
2016	28.523
2017	28.735
2018	29.429
2019	30.144
2020	30.821
2021	31.528
2022	32.16