Year	Percent
1991	15.185
1992	16.26
1993	17.983
1994	20.286
1995	19.302
1996	20.031
1997	20.734
1998	21.958
1999	21.064
2000	18.649
2001	19.758
2002	19.057
2003	16.546
2004	17.814
2005	17.256
2006	18.631
2007	18.097
2008	16.515
2009	19.056
2010	20.012
2011	19.712
2012	19.18
2013	19.637
2014	20.737
2015	19.046
2016	17.26
2017	17.643
2018	17.418
2019	17.35
2020	17.301
2021	17.304
2022	17.303