Year	Percent
1991	63.31993
1992	62.98642
1993	62.66384
1994	62.17826
1995	61.75973
1996	61.34995
1997	61.11618
1998	60.71752
1999	60.08831
2000	59.64581
2001	59.10144
2002	58.59677
2003	57.75965
2004	56.77606
2005	55.99635
2006	55.07682
2007	54.10752
2008	53.51366
2009	52.50731
2010	51.5294
2011	49.26698
2012	47.01002
2013	46.50801
2014	45.89407
2015	45.26294
2016	44.56476
2017	43.93426
2018	43.32876
2019	42.63435