Year	Percent
1977	2.13311
1978	3.32738
1979	4.80511
1980	6.03836
1981	3.85641
1982	7.3577
1983	11.79798
1984	12.42718
1985	11.4709
1986	8.32049
1987	7.23861
1988	8.09123
1989	5.18442
1990	4.32531
1991	3.96467
1992	6.29187
1993	7.91725
1994	7.29628
1995	6.20154
1996	6.14764
1997	5.14813
1998	6.7341
1999	5.35062
2000	6.03383
2001	8.57933
2002	16.08037
2003	16.97942
2004	14.49429
2005	6.62487
2006	8.83277
2007	8.85909
2008	10.10963
2009	12.34378
2010	14.38713
2011	12.98179
2012	7.54328
2013	16.62488
2014	4.49699
2015	4.64218
2016	5.73472