Year	Percent
1991	74.554
1992	73.3
1993	71.98
1994	70.666
1995	69.399
1996	68.202
1997	67.002
1998	65.772
1999	64.557
2000	63.31
2001	62.148
2002	60.954
2003	59.731
2004	58.487
2005	57.225
2006	55.935
2007	54.619
2008	53.276
2009	51.929
2010	50.571
2011	49.222
2012	47.873
2013	46.51
2014	44.972
2015	45.291
2016	45.49
2017	45.183
2018	44.85
2019	44.495
2020	44.13
2021	43.754
2022	43.367