Year	Percent
1990	9.39
1991	16.418
1992	25.946
1993	31.073
1994	31.515
1995	41.3035
1996	41.8767
1997	34.1906
1998	33.9759
1999	27.5438
2000	27.4896
2001	25.6989
2002	28.6432
2003	27.752
2004	27.8651
2005	20.6298
2006	19.0226
2007	16.4421
2008	17.135
2009	24.1478
2010	23.7763
2011	21.7637
2012	19.933
2013	22.9296
2014	22.7982
2015	25.3599
2016	21.7638
2017	20.948