Year	Percent
1991	42.405
1992	42.255
1993	41.553
1994	41.59
1995	42.667
1996	42.859
1997	41.901
1998	41.585
1999	39.272
2000	37.257
2001	37.977
2002	38.341
2003	39.024
2004	40.466
2005	40.344
2006	42.527
2007	44.6
2008	46.028
2009	44.903
2010	43.115
2011	42.444
2012	42.639
2013	42.781
2014	43.572
2015	44.541
2016	44.437
2017	44.93
2018	45.492
2019	45.685
2020	45.849
2021	45.928
2022	45.967