Year	Percent
1991	40.657
1992	40.036
1993	39.832
1994	39.445
1995	39.835
1996	40.407
1997	41.085
1998	41.782
1999	42.358
2000	41.965
2001	41.413
2002	40.884
2003	40.329
2004	39.796
2005	40.569
2006	39.855
2007	39.707
2008	39.562
2009	39.425
2010	36.516
2011	35.766
2012	35.896
2013	35.737
2014	35.335
2015	36.182
2016	36.779
2017	36.214
2018	35.721
2019	35.485
2020	35.085
2021	34.549
2022	34.074