Year	Percent
1991	57.725
1992	57.588
1993	57.536
1994	57.264
1995	56.97
1996	56.084
1997	55.187
1998	55.17
1999	55.643
2000	56.166
2001	55.685
2002	55.317
2003	55.82
2004	54.843
2005	52.402
2006	50.332
2007	50.1
2008	49.924
2009	49.741
2010	48.918
2011	49.234
2012	48.209
2013	48.028
2014	47.618
2015	48.302
2016	48.1
2017	47.892
2018	47.822
2019	47.747
2020	47.669
2021	47.592
2022	47.513