Year	Percent
1991	18.7203
1992	19.03229
1993	18.65272
1994	18.2814
1995	17.4605
1996	17.27904
1997	21.58473
1998	19.02839
1999	17.49161
2000	14.92553
2001	15.47092
2002	16.22878
2003	14.24369
2004	13.30132
2005	12.05117
2006	11.46095
2007	10.17988
2008	7.95705
2009	8.7509
2010	8.61442
2011	8.89508
2012	8.3733
2013	8.0562
2014	7.5037
2015	7.93921
2016	7.69173
2017	6.86765
2018	6.97217
2019	7.29035