Year	Percent
1991	19.56
1992	20.611
1993	20.199
1994	21.601
1995	21.891
1996	22.054
1997	21.887
1998	21.994
1999	21.791
2000	22.675
2001	22.912
2002	23.428
2003	21.931
2004	16.774
2005	19.429
2006	19.999
2007	18.874
2008	19.607
2009	19.638
2010	19.38
2011	18.716
2012	17.134
2013	17.705
2014	18.445
2015	18.108
2016	17.186
2017	16.859
2018	16.473
2019	16.127
2020	15.809
2021	15.483
2022	15.129