Year	Percent
1978	0.45578
1979	0.67665
1980	1.06566
1981	1.37725
1982	3.14408
1983	2.51946
1984	3.5956
1985	4.02906
1986	3.46617
1987	3.25376
1988	2.86467
1989	3.12717
1990	3.25546
1991	4.18366
1992	4.1942
1993	6.89362
1994	7.42359
1995	6.15709
1996	6.57383
1997	7.63153
1998	7.24608
1999	7.98139
2000	7.18397
2001	6.72293
2002	6.51015
2003	7.80028
2004	10.19781
2005	11.31754
2006	14.77964
2007	12.31897
2008	13.94016
2009	17.55116
2010	18.51971
2011	18.24584
2012	18.06889
2013	15.65682
2014	10.90909
2015	11.98653
2016	10.92809