Year	Percent
1991	45.625
1992	46.908
1993	44.172
1994	39.408
1995	40.896
1996	42.846
1997	39.339
1998	39.274
1999	37.679
2000	37.026
2001	37.203
2002	36.516
2003	37.17
2004	38.699
2005	39.633
2006	41.455
2007	42.144
2008	44.289
2009	45.637
2010	45.809
2011	45.775
2012	46.13
2013	46.417
2014	46.986
2015	47.457
2016	47.33
2017	47.601
2018	47.709
2019	47.854
2020	47.97
2021	48.142
2022	48.295