Year	Percent
1991	41.568
1992	41.155
1993	40.788
1994	40.156
1995	40.366
1996	39.985
1997	40.623
1998	41.026
1999	40.171
2000	40.531
2001	40.716
2002	40.353
2003	40.458
2004	39.594
2005	40.236
2006	40.397
2007	40.917
2008	41.074
2009	41.46
2010	41.344
2011	41.043
2012	40.835
2013	40.042
2014	39.928
2015	39.195
2016	38.963
2017	39.007
2018	38.948
2019	38.887
2020	38.816
2021	38.747
2022	38.69