Year	Percent
1991	53.398
1992	55.353
1993	56.148
1994	54.856
1995	55.03
1996	54.359
1997	54.134
1998	52.784
1999	52.377
2000	52.076
2001	52.037
2002	52.293
2003	51.562
2004	51.667
2005	51.626
2006	39.553
2007	39.58
2008	36.129
2009	36.15
2010	36.182
2011	36.038
2012	36.002
2013	36.001
2014	35.433
2015	35.685
2016	35.793
2017	35.838
2018	35.798
2019	35.757
2020	35.71
2021	35.663
2022	35.621