Year	Percent
1991	40.462
1992	41.844
1993	41.779
1994	42.427
1995	42.878
1996	41.98
1997	42.726
1998	44.303
1999	43.733
2000	42.968
2001	42.75
2002	41.534
2003	41.577
2004	43.85
2005	44.413
2006	45.723
2007	47
2008	48.576
2009	49.452
2010	50.094
2011	51.441
2012	51.154
2013	50.452
2014	51.285
2015	50.788
2016	50.644
2017	50.799
2018	50.808
2019	50.819
2020	50.817
2021	50.83
2022	50.851