Year	Percent
1991	63.43567
1992	63.65692
1993	64.41839
1994	64.45237
1995	64.30937
1996	64.69257
1997	64.99469
1998	65.21904
1999	65.48079
2000	65.85593
2001	66.3058
2002	64.42692
2003	63.70367
2004	63.26266
2005	62.12938
2006	61.27571
2007	60.11604
2008	59.29742
2009	56.8945
2010	54.59523
2011	53.57029
2012	51.40065
2013	49.82333
2014	48.41316
2015	47.06974
2016	45.80591
2017	43.98905
2018	43.12617
2019	42.53458