Year	Percent
1991	13.276
1992	13.767
1993	15.225
1994	17.623
1995	16.926
1996	16.904
1997	18.715
1998	19.231
1999	18.478
2000	16.088
2001	17.108
2002	16.273
2003	14.028
2004	15.634
2005	15.157
2006	16.216
2007	15.9
2008	14.126
2009	16.212
2010	17.283
2011	16.847
2012	16.27
2013	16.905
2014	18.592
2015	16.522
2016	14.223
2017	14.569
2018	14.36
2019	14.291
2020	14.241
2021	14.236
2022	14.227