Year	Percent
1991	28.158
1992	22.707
1993	22.215
1994	21.949
1995	21.63
1996	20.614
1997	18.931
1998	20.823
1999	21.012
2000	20.706
2001	16.825
2002	16.736
2003	16.068
2004	16.775
2005	17.064
2006	17.132
2007	17.409
2008	16.621
2009	15.948
2010	17.07
2011	16.348
2012	15.19
2013	15.701
2014	14.555
2015	15.24
2016	14.135
2017	13.735
2018	13.352
2019	12.964
2020	12.62
2021	12.284
2022	11.995