Year	Percent
1991	8.538
1992	8.097
1993	7.891
1994	7.993
1995	8.193
1996	8.585
1997	7.733
1998	7.234
1999	6.959
2000	6.379
2001	6.282
2002	6.081
2003	5.779
2004	4.863
2005	5.285
2006	5.285
2007	5.617
2008	5.233
2009	5.201
2010	4.993
2011	4.655
2012	4.241
2013	4.183
2014	4.567
2015	4.209
2016	3.929
2017	3.889
2018	3.788
2019	3.706
2020	3.615
2021	3.544
2022	3.473