Year	Percent
1991	54.821
1992	50.893
1993	47.487
1994	46.633
1995	45.912
1996	46.146
1997	46.462
1998	47.521
1999	49.16
2000	49.452
2001	50.449
2002	51.082
2003	50.911
2004	50.359
2005	51.747
2006	52.471
2007	53.341
2008	53.595
2009	52.705
2010	51.746
2011	51.85
2012	51.999
2013	51.329
2014	51.095
2015	50.611
2016	50.239
2017	50.208
2018	50.307
2019	50.275
2020	50.1
2021	49.913
2022	49.725