Year	Percent
1991	55.728
1992	54.814
1993	54.719
1994	54.458
1995	54.002
1996	53.726
1997	52.922
1998	52.734
1999	52.304
2000	51.828
2001	51.432
2002	50.807
2003	50.253
2004	49.922
2005	49.407
2006	48.739
2007	47.997
2008	47.482
2009	47.138
2010	46.863
2011	46.197
2012	45.334
2013	44.816
2014	44.567
2015	44.188
2016	43.827
2017	43.977
2018	43.899
2019	43.822
2020	43.744
2021	43.67
2022	43.595