Year	Percent
1991	15.412
1992	15.361
1993	15.657
1994	15.552
1995	15.296
1996	15.11
1997	15.615
1998	14.951
1999	14.439
2000	14.612
2001	14.723
2002	14.826
2003	14.409
2004	14.124
2005	14.353
2006	13.643
2007	13.288
2008	13.432
2009	13.126
2010	13.329
2011	12.998
2012	12.71
2013	12.273
2014	12.618
2015	12.621
2016	12.658
2017	12.374
2018	12.466
2019	12.429
2020	12.346
2021	12.254
2022	12.152