Year	Percent
1973	15.97
1974	6.493
1975	2.494
1976	2.686
1977	2.775
1978	0.7738
1979	1.287
1980	0.7011
1981	0.8081
1982	0.1178
1983	0.5701
1984	0.4591
1985	2.878
1986	0.2008
1988	2.467
1989	1.761
1990	1.23
1991	3.684
1992	3.447
1993	0.8764
1994	2.893
1995	2.022
1996	5.575
1997	16.05
1998	13.84
1999	16.05
2000	24.21
2001	21.03
2002	21.33
2003	23.54
2004	27.25
2005	24.01
2006	21.9
2007	25.31