Year	Percent
1991	53.775
1992	52.66
1993	51.953
1994	51.26
1995	50.931
1996	49.943
1997	49.258
1998	49.135
1999	48.352
2000	47.481
2001	46.297
2002	45.995
2003	45.413
2004	44.372
2005	44.118
2006	43.534
2007	43.465
2008	43.156
2009	43.232
2010	42.638
2011	41.995
2012	41.774
2013	41.346
2014	39.891
2015	38.711
2016	38.496
2017	38.776
2018	37.806
2019	36.862
2020	36.003
2021	35.193
2022	34.505