Year	Percent
1977	15.5893
1978	15.34499
1979	9.6897
1980	23.69922
1981	39.78869
1982	45.8202
1983	22.05907
1984	19.34272
1985	21.7216
1986	15.31944
1987	22.58558
1988	13.32013
1989	5.47942
1990	5.0047
1991	156.85805
1992	35.75063
1993	36.74208
1994	42.36794
1995	46.74886
1996	33.63694
1997	40.3656
1998	29.88437
1999	21.73402
2000	29.40465
2001	35.94785
2002	17.2014
2003	19.02972
2004	10.6934
2005	12.13052
2006	7.79116
2007	15.9879
2008	14.44505
2009	16.46697
2010	16.14303
2011	16.59821
2012	13.34427
2013	12.79717
2014	13.17216
2015	15.61147
2016	15.96241