Year	Percent
1991	53.32472
1992	53.23583
1993	53.1591
1994	53.08564
1995	52.95287
1996	52.7444
1997	52.48914
1998	52.23991
1999	51.97049
2000	51.57108
2001	51.12903
2002	50.6598
2003	50.12412
2004	49.62972
2005	49.05438
2006	48.38126
2007	47.59694
2008	46.88059
2009	46.19041
2010	45.69637
2011	44.60178
2012	43.63212
2013	42.84412
2014	42.13064
2015	41.25653
2016	40.3736
2017	39.51254
2018	38.9296
2019	38.38226