Year	% of total
1970	54.04933627184282
1971	54.38431724619448
1972	53.63505140792641
1973	54.34635247333004
1974	53.70388471099601
1975	57.31060142545081
1976	56.696225892318274
1977	55.54067458589491
1978	53.96425754129387
1979	52.417219006780016
1980	49.17582935447234
1981	46.8565276645822
1982	42.854344069909544
1983	39.37975004743709
1984	38.89774336265772
1985	37.69784053310951
1986	37.561156412602806
1987	37.45724346513923
1988	38.56155141980491
1989	36.839462251918526
1990	38.21782178217822
1991	37.57575757575757
1992	56.61538461538461
1993	71.83673469387755
1994	67.3469387755102
1995	60.98654708520179
1996	45.41832669322709
1997	46.95945945945946
1998	44.47852760736196
1999	44.15204678362573
2000	43.85474860335196
2001	42.45810055865922
2002	48.8135593220339
2003	48.742138364779876
2004	48.214285714285715
2005	47.687861271676304
2006	49.45054945054945
2007	44.61942257217848
2008	42.30769230769231