Year	Percent
1991	36.344
1992	36.072
1993	36.426
1994	33.508
1995	33.755
1996	34.574
1997	34.025
1998	35.044
1999	32.977
2000	33.112
2001	34.228
2002	35.192
2003	34.417
2004	34.506
2005	35.414
2006	35.934
2007	35.45
2008	35.06
2009	34.697
2010	36.569
2011	36.608
2012	35.959
2013	36.272
2014	36.177
2015	37.072
2016	36.651
2017	35.404
2018	35.255
2019	35.699
2020	36.384
2021	37.358
2022	38.023