Year	Percent
1991	16.631
1992	17.094
1993	17.229
1994	18.43
1995	18.152
1996	16.424
1997	16.643
1998	16.407
1999	16.509
2000	19.027
2001	19.3
2002	19.625
2003	18.657
2004	18.59
2005	17.954
2006	17.834
2007	17.91
2008	17.791
2009	16.872
2010	16.922
2011	17.46
2012	15.899
2013	15.848
2014	14.988
2015	15.694
2016	15.425
2017	14.991
2018	14.637
2019	14.237
2020	13.782
2021	13.283
2022	12.741