Year	Percent
1991	9.713
1992	10.619
1993	10.877
1994	10.114
1995	9.893
1996	9.915
1997	16.171
1998	14.747
1999	18.2
2000	20.678
2001	25.07
2002	29.116
2003	29.728
2004	35.127
2005	38.36
2006	39.111
2007	40.537
2008	42.7
2009	39.166
2010	39.024
2011	39.295
2012	38.892
2013	39.695
2014	39.056
2015	38.002
2016	37.906
2017	37.344
2018	36.593
2019	36.426
2020	35.943
2021	36.003
2022	35.891