Year	Percent
1991	47.963
1992	47.962
1993	47.826
1994	48
1995	48.217
1996	48.89
1997	49.568
1998	49.873
1999	50.477
2000	50.952
2001	51.178
2002	51.597
2003	51.718
2004	52.036
2005	52.367
2006	52.401
2007	52.224
2008	52.455
2009	51.924
2010	51.64
2011	51.445
2012	51.659
2013	52.192
2014	53.141
2015	53.656
2016	54.119
2017	54.423
2018	54.65
2019	54.694
2020	54.64
2021	54.557
2022	54.447