Year	Percent
1991	14.16
1992	14.208
1993	11.724
1994	9.412
1995	9.301
1996	9.459
1997	9.467
1998	9.262
1999	9.055
2000	9.214
2001	9.375
2002	9.729
2003	10.135
2004	10.426
2005	10.713
2006	11.202
2007	11.53
2008	11.878
2009	13.013
2010	13.913
2011	15.063
2012	16.051
2013	16.082
2014	16.975
2015	18.338
2016	18.772
2017	18.982
2018	19.192
2019	19.356
2020	19.587
2021	19.755
2022	19.926