Year	Percent
1991	48.968
1992	53.764
1993	54.662
1994	54.205
1995	55.665
1996	56.994
1997	55.684
1998	55.014
1999	54.902
2000	54.032
2001	52.319
2002	49.717
2003	48.194
2004	47.853
2005	46.843
2006	45.787
2007	42.81
2008	41.875
2009	41.172
2010	34.698
2011	33.496
2012	35.813
2013	31.083
2014	29.475
2015	29.721
2016	32.424
2017	32.434
2018	31.819
2019	30.921
2020	30.097
2021	28.933
2022	27.587