Year	Percent
1991	10.697
1992	12.533
1993	15.952
1994	16.845
1995	16.331
1996	14.642
1997	12.551
1998	11.963
1999	12.268
2000	12.427
2001	11.621
2002	11.428
2003	10.963
2004	9.639
2005	8.456
2006	8.584
2007	9.039
2008	7.831
2009	7.05
2010	7.081
2011	6.685
2012	6.234
2013	6.192
2014	7.759
2015	7.323
2016	7.143
2017	7.12
2018	6.9
2019	6.707
2020	6.536
2021	6.35
2022	6.172