Year	Percent
1991	42.864
1992	43.005
1993	40.798
1994	38.9
1995	38.804
1996	35.862
1997	36.589
1998	37.358
1999	37.906
2000	37.607
2001	36.329
2002	36.136
2003	35.747
2004	36.755
2005	38.866
2006	40.019
2007	41.496
2008	43.008
2009	42.372
2010	40.736
2011	38.178
2012	36.94
2013	35.876
2014	36.25
2015	36.212
2016	36.273
2017	36.095
2018	35.966
2019	35.856
2020	35.778
2021	35.718
2022	35.653