Year	% of total
1970	7.990490748736831
1971	9.17526628030146
1972	8.645325878248983
1973	8.237407752537973
1974	10.170965149539606
1975	9.61430923771384
1976	9.632475712620565
1977	8.847102428044002
1978	8.283591012449723
1979	9.363425026719666
1980	8.96908724201982
1981	8.60902268786127
1982	8.763889517641614
1983	6.822813572443555
1984	8.633940154389665
1985	9.220955809652637
1986	8.815262428012069
1987	8.203656225585759
1988	9.151089593818236
1989	10.331381785648603
1990	3.3069734004313442
1991	3.358992302309307
1992	3.3178500331785004
1993	3.203943314849045
1994	3.3169533169533167
1995	3.9769082745349587
1996	4.441624365482234
1997	5.091383812010443
1998	5.516356638871072
1999	5.771567436208992
2000	6.589891234804862
2001	6.625386996904024
2002	6.524317912218268
2003	6.232914160743576
2004	6.614349775784753
2005	7.060185185185184
2006	7.02054794520548
2007	6.414899120538024
2008	6.631299734748011