Year	% of total
1970	71.906798500854
1971	55.19772401825467
1972	57.09618359049373
1973	58.70902712091648
1974	53.72682191603969
1975	59.87467095835355
1976	57.203389061231846
1977	59.41951488908249
1978	60.589517147360425
1979	68.30272926387863
1980	62.747807411836696
1981	58.75896812897321
1982	62.46236541090181
1983	61.483982086240566
1984	52.216485347871476
1985	52.5628416212208
1986	50.83055503759187
1987	60.786123079853006
1988	47.32520274093576
1989	51.4056086567943
1990	72.97428432799612
1991	71.7546362339515
1992	70.56357708430367
1993	69.2237023426734
1994	68.07935076645627
1995	66.82991985752449
1996	64.04494382022472
1997	63.1578947368421
1998	64.76437527021184
1999	62.47201074787282
2000	62.56521739130435
2001	60.561056105610554
2002	59.87795575896262
2003	60.82650273224044
2004	58.922670191672175
2005	56.95917711346834
2006	52.694034637588196
2007	52.03808390360012
2008	48.79976580796253