Year	% of total
1970	4.823609973985426
1971	4.863614408046842
1972	5.652229471440124
1973	5.255055447305065
1974	5.028315996884505
1975	4.83525130488632
1976	4.750730974056179
1977	4.649725351110941
1978	4.827350224478584
1979	4.919422508317661
1980	4.926474689055905
1981	5.036097091999428
1982	4.876279951179973
1983	5.040067616177328
1984	4.629187216729045
1985	4.302347793315783
1986	4.014456573683588
1987	3.8588299561246577
1988	3.8143153494488975
1989	3.788616967012316
1990	12.307692307692308
1991	10.94224924012158
1992	9.6875
1993	8.4375
1994	7.357859531772576
1995	5.88235294117647
1996	5.167173252279635
1997	4.735376044568245
1998	4.123711340206185
1999	3.614457831325301
2000	4.143646408839778
2001	4.658385093167702
2002	4.054054054054054
2003	3.90625
2004	3.937007874015748
2005	3.7783375314861463
2006	9.852216748768473
2007	15.294117647058824
2008	18.997912317327767