Year	Percent
1991	54.812
1992	55.807
1993	54.725
1994	55.069
1995	54.98
1996	55.798
1997	52.15
1998	49.712
1999	49.12
2000	49.08
2001	49.633
2002	49.417
2003	49.049
2004	48.982
2005	49.14
2006	49.399
2007	48.316
2008	48.837
2009	49.225
2010	49.019
2011	48.596
2012	49.967
2013	49.708
2014	49.864
2015	50.253
2016	50.395
2017	50.011
2018	50.298
2019	50.571
2020	50.742
2021	50.967
2022	51.181