Year	Percent
1973	28.76453
1974	10.99019
1975	8.82264
1976	14.48941
1977	10.35705
1978	11.39199
1979	13.94121
1980	8.71028
1981	3.79355
1982	4.22095
1983	10.21047
1984	7.36376
1985	5.45475
1986	5.49492
1987	8.9983
1988	10.47606
1989	4.97237
1990	5.36591
1991	10.06292
1992	13.80315
1993	17.32059
1994	20.49509
1995	15.10145
1996	12.32428
1997	11.29753
1998	12.48092
1999	9.93419
2000	9.71483
2001	8.71524
2002	10.31599
2003	14.23102
2004	16.34018
2005	15.26569
2006	19.22944
2007	24.4611
2008	24.72428
2009	40.65466
2010	41.57189
2011	33.63584
2012	44.65927
2013	53.20732
2014	62.58633
2015	71.0627
2016	78.50051