Year	% of total
1970	67.85501577696935
1971	52.745105457988984
1972	56.35858085710903
1973	59.63973114140999
1974	56.31011211290663
1975	62.8671571247121
1976	62.120886023014776
1977	67.15280704634843
1978	70.00565268253183
1979	76.39763164277265
1980	76.38829060322693
1981	77.04679614492362
1982	80.74186701139799
1983	82.30901085086279
1984	83.09452377375153
1985	87.45835122496028
1986	87.49230705342018
1987	88.16681854110094
1988	87.25730733962959
1989	87.63187982760469
1990	99.08136482939632
1991	99.08316961362148
1992	99.08616187989556
1993	99.01768172888016
1994	99.01445466491458
1995	98.94806048652202
1996	98.75730994152046
1997	98.73511904761905
1998	98.78869448183042
1999	98.61717612809315
2000	98.58757062146893
2001	98.55172413793103
2002	98.53503184713375
2003	98.66666666666667
2004	98.61954721148537
2005	98.54096520763187
2006	98.23815309842041
2007	98.24063564131669
2008	97.96407185628743