Year	Percent
1991	42.56999
1992	42.46141
1993	42.2372
1994	42.25978
1995	41.8811
1996	41.57566
1997	41.59379
1998	41.34843
1999	40.9796
2000	41.01699
2001	40.80616
2002	40.42542
2003	39.76911
2004	39.18563
2005	38.41366
2006	37.30185
2007	37.05804
2008	36.74135
2009	36.3818
2010	35.92528
2011	35.35759
2012	34.76854
2013	34.22238
2014	33.64795
2015	33.01238
2016	32.6112
2017	32.05825
2018	31.59608
2019	30.89393