Year	Percent
1991	60.217
1992	58.361
1993	56.442
1994	54.425
1995	52.236
1996	51.011
1997	49.64
1998	48.214
1999	46.889
2000	45.842
2001	47.369
2002	49.279
2003	51.646
2004	53.013
2005	53.953
2006	56.667
2007	56.025
2008	56.218
2009	55.134
2010	56.44
2011	56.688
2012	56.008
2013	56.638
2014	56.354
2015	55.5
2016	54.018
2017	53.812
2018	53.452
2019	53.031
2020	52.611
2021	51.948
2022	51.389