Year	Percent
1991	45.279
1992	45.561
1993	46.576
1994	47.549
1995	44.355
1996	42.994
1997	41.795
1998	41.65
1999	41.224
2000	41.025
2001	41.432
2002	40.987
2003	39.835
2004	39.208
2005	38.821
2006	38.898
2007	39.318
2008	41.564
2009	38.713
2010	39.82
2011	42.22
2012	41.857
2013	42.624
2014	42.045
2015	42.071
2016	38.839
2017	38.996
2018	38.96
2019	38.737
2020	38.445
2021	38.124
2022	37.759