Year	Percent
1991	48.91349
1992	48.83791
1993	48.73683
1994	48.63593
1995	48.35743
1996	48.14995
1997	47.84873
1998	47.3582
1999	46.77857
2000	46.32145
2001	45.62988
2002	45.0974
2003	44.17117
2004	43.24693
2005	42.34151
2006	41.61547
2007	40.7025
2008	39.8385
2009	39.06752
2010	38.18688
2011	37.40183
2012	36.39151
2013	35.48965
2014	34.34731
2015	33.3328
2016	32.48681
2017	31.62232
2018	30.83148
2019	30.09103