Year	Percent
1991	13.676
1992	13.335
1993	13.862
1994	13.916
1995	14.254
1996	14.591
1997	14.884
1998	15.12
1999	15.314
2000	16.41
2001	16.7
2002	16.908
2003	17.135
2004	17.501
2005	17.984
2006	18.204
2007	18.196
2008	18.717
2009	19.722
2010	20.719
2011	21.248
2012	23.677
2013	25.272
2014	26.177
2015	27.082
2016	27.855
2017	28.285
2018	29.415
2019	30.449
2020	31.101
2021	31.711
2022	32.386