Year	Percent
1977	1.46616
1978	3.0911
1979	6.23786
1980	5.13877
1981	1.77464
1982	1.15399
1983	1.33324
1984	1.48017
1985	2.30254
1986	1.43412
1987	1.27637
1988	2.02251
1989	4.17276
1990	2.55765
1991	9.82485
1992	8.13987
1993	18.60902
1994	14.3207
1995	14.64307
1996	16.42197
1997	20.23221
1998	15.1641
1999	19.69772
2000	16.12904
2001	12.42442
2002	16.95694
2003	27.42805
2004	24.65346
2005	23.94636
2006	22.03334
2007	19.84838
2008	11.02184
2009	13.73819
2010	15.08632
2011	8.22007
2012	6.27397
2013	9.61999
2014	11.4269
2015	9.43837
2016	11.46253
2017	17.05484