Year	Percent
1981	4.08064
1982	17.45962
1983	13.03281
1984	17.67562
1985	33.14982
1986	12.70974
1987	181.45003
1988	48.32547
1989	47.3756
1990	34.05504
1991	91.22635
1992	32.53051
1993	47.94288
1994	50.85983
1995	49.80202
1996	35.18542
1997	10.62273
1998	6.01394
1999	8.56736
2000	10.90252
2001	14.62033
2002	10.95675
2003	4.91611
2004	7.49373
2005	6.19767
2006	7.90487
2007	6.71352
2008	7.98232
2009	1.07613
2010	7.64403
2011	3.33213
2012	5.85461
2013	3.91751
2014	2.6337
2015	4.38128
2016	12.2604
2017	9.77202