Year	Percent
1991	71.126
1992	70.247
1993	69.279
1994	68.314
1995	67.333
1996	66.336
1997	65.371
1998	64.359
1999	63.243
2000	62.144
2001	60.973
2002	59.831
2003	58.621
2004	56.915
2005	55.188
2006	56.132
2007	53.204
2008	51.117
2009	49.099
2010	47.029
2011	45.081
2012	43.159
2013	41.296
2014	39.459
2015	39.253
2016	39.084
2017	38.897
2018	38.707
2019	38.516
2020	38.326
2021	38.137
2022	37.945