Year	Percent
1991	19.227
1992	15.59
1993	18.372
1994	16.527
1995	21.869
1996	21.886
1997	23.064
1998	20.79
1999	20.805
2000	18.103
2001	18.09
2002	19.732
2003	19.815
2004	17.532
2005	17.635
2006	16.031
2007	14.794
2008	12.661
2009	13.405
2010	14.409
2011	14.118
2012	14.222
2013	13.714
2014	13.851
2015	13.422
2016	12.782
2017	12.817
2018	13.159
2019	13.587
2020	14.005
2021	14.42
2022	14.789