Year	Percent
1981	25.16883
1982	42.59764
1983	44.94997
1984	52.27871
1985	55.17184
1986	62.58769
1987	70.3949
1988	71.16155
1989	68.93138
1990	71.40019
1991	68.21003
1992	89.70525
1993	111.25496
1994	147.18117
1995	135.77936
1996	118.66557
1997	118.82119
1998	133.65296
1999	72.8565
2000	67.41725
2001	70.24197
2002	84.03574
2003	85.09192
2004	65.79488
2005	50.37715
2006	14.96307
2007	13.4635
2008	10.72205
2009	16.71883
2010	24.59137
2011	27.00492
2012	24.20923
2013	26.45089
2014	29.44131
2015	31.36929
2016	31.97825