Year	Percent
1981	2.94558
1982	12.91921
1983	5.88062
1984	6.19481
1985	5.5281
1986	10.06677
1987	11.25003
1988	30.2503
1989	37.07527
1990	31.26766
1991	28.88693
1992	29.70922
1993	23.27553
1994	25.27476
1995	30.9631
1996	45.28274
1997	57.37631
1998	61.22678
1999	57.97999
2000	60.48663
2001	40.91384
2002	50.26551
2003	55.38959
2004	60.79492
2005	52.17017
2006	42.33151
2007	40.34896
2008	21.22951
2009	19.92067
2010	39.74663
2011	39.53103
2012	35.79545
2013	42.48613
2014	59.17952
2015	59.57385
2016	41.3739