Year	Percent
1991	42.45615
1992	42.33916
1993	42.14516
1994	41.90646
1995	41.57951
1996	41.29338
1997	41.22828
1998	40.68608
1999	39.95001
2000	38.9391
2001	44.2041
2002	42.38948
2003	35.08673
2004	35.08657
2005	38.61407
2006	39.49996
2007	36.10019
2008	31.20414
2009	30.08599
2010	29.99737
2011	29.78473
2012	27.79103
2013	29.22806
2014	30.85224
2015	27.84844
2016	29.68222
2017	30.48856
2018	31.06441
2019	30.54233