Year	% of total
1970	4.441276076357906
1971	4.66690762102395
1972	5.180173692241343
1973	5.509715648542535
1974	6.385278433209818
1975	6.54452683513714
1976	6.292977193365344
1977	6.272599084191111
1978	6.391202489182944
1979	6.389973208950647
1980	6.407536054797703
1981	6.17233099730712
1982	6.253073139872094
1983	7.004975147697999
1984	7.6751038828171305
1985	7.530234341607049
1986	7.4648717888508145
1987	7.480010401266298
1988	7.528337757203382
1989	7.413274522729648
1990	2.9702970297029703
1991	3.3333333333333335
1992	3.8834951456310676
1993	4.449648711943794
1994	4.98812351543943
1995	5.4245283018867925
1996	4.910714285714286
1997	4.477611940298507
1998	3.8934426229508197
1999	3.4951456310679614
2000	3.177570093457944
2001	3.136531365313653
2002	3.2846715328467155
2003	3.2200357781753133
2004	3.25497287522604
2005	3.3868092691622103
2006	4.4673539518900345
2007	5.689655172413794
2008	7.4074074074074066