Year	Percent
1991	17.057
1992	16.988
1993	16.71
1994	18.407
1995	17.796
1996	15.756
1997	14.322
1998	16.902
1999	13.508
2000	10.951
2001	10.43
2002	8.453
2003	7.793
2004	8.27
2005	8.603
2006	8.826
2007	9.633
2008	9.858
2009	9.48
2010	9.504
2011	8.291
2012	8.909
2013	10.411
2014	10.936
2015	11.68
2016	11.874
2017	12.357
2018	12.441
2019	12.59
2020	12.622
2021	12.598
2022	12.551