Year	Percent
1991	39.476
1992	41.586
1993	42.075
1994	42.93
1995	43.207
1996	44.415
1997	46.172
1998	47.638
1999	49.576
2000	51.375
2001	52.829
2002	53.303
2003	53.499
2004	53.265
2005	53.772
2006	54.698
2007	56.3
2008	57.455
2009	57.678
2010	55.622
2011	54.945
2012	54.972
2013	54.264
2014	53.329
2015	53.972
2016	54.239
2017	54.917
2018	55.534
2019	55.709
2020	55.617
2021	55.535
2022	55.443