Year	% of total
1970	3.6604475731955874
1971	3.8222930965826816
1972	2.8513966925149856
1973	4.093181264479332
1974	4.8615955758849365
1975	5.895114925490954
1976	5.62915037026927
1977	5.965749479097603
1978	6.51102210579184
1979	6.442561707787722
1980	6.663867723049975
1981	6.110087544617595
1982	6.1259424450259194
1983	6.513820696006622
1984	6.130006793724134
1985	5.752996572831632
1986	5.313007839269292
1987	5.389359117504515
1988	5.472072535674015
1989	5.5259413689210355
1990	5.8982683982683985
1991	5.990783410138248
1992	6.229720960415315
1993	5.808257522743177
1994	5.177514792899409
1995	5.769230769230769
1996	6.036217303822937
1997	6.228373702422145
1998	7.202216066481995
1999	6.557377049180328
2000	8.116385911179174
2001	7.230559345156889
2002	5.0212765957446805
2003	7.602339181286549
2004	7.225130890052355
2005	7.560483870967742
2006	7.649769585253456
2007	9.15492957746479
2008	8.622398414271556