Year	Percent
1991	16.038
1992	15.712
1993	15.938
1994	16.042
1995	15.901
1996	15.461
1997	15.654
1998	17.084
1999	16.705
2000	16.101
2001	16.131
2002	15.867
2003	16.45
2004	16.54
2005	16.367
2006	16.767
2007	17.271
2008	17.311
2009	16.883
2010	17.288
2011	16.763
2012	16.649
2013	16.934
2014	16.829
2015	16.677
2016	16.554
2017	17.284
2018	17.131
2019	17.039
2020	17.024
2021	17.011
2022	16.995