Year	Percent
1991	30.412
1992	30.233
1993	30.266
1994	30.173
1995	29.934
1996	30.036
1997	29.967
1998	29.687
1999	29.962
2000	30.059
2001	30.291
2002	30.731
2003	30.528
2004	30.087
2005	29.997
2006	29.294
2007	28.621
2008	28.835
2009	28.149
2010	27.674
2011	26.602
2012	26.164
2013	25.965
2014	25.802
2015	25.626
2016	24.684
2017	24.392
2018	24.123
2019	23.829
2020	23.466
2021	23.126
2022	22.828