Year	Percent
1971	79.26791
1972	77.73311
1973	110.85129
1974	298.18382
1975	435.30697
1976	192.65371
1977	88.98916
1978	51.76343
1979	54.71687
1980	45.4684
1981	39.56209
1982	36.71204
1983	31.3531
1984	33.69701
1985	39.60533
1986	31.78296
1987	33.28943
1988	22.4306
1989	26.87374
1990	38.38297
1991	43.13385
1992	35.35436
1993	36.47465
1994	33.72578
1995	29.97744
1996	46.08215
1997	44.3175
1998	33.3387
1999	34.74851
2000	37.18742
2001	31.0077
2002	32.60314
2003	54.63875
2004	59.7247
2005	65.70715
2006	81.287
2007	57.49957
2008	64.34396
2009	40.57539
2010	29.1507
2011	23.63905
2012	22.559
2013	15.31988
2014	15.80499
2015	12.56195
2016	8.9804