Year	% of total
1970	78.93393363986033
1971	79.71552012961838
1972	79.65602300742837
1973	79.20054204654309
1974	79.02031681222292
1975	79.42083882652999
1976	79.14918544863066
1977	78.58895524258148
1978	78.50160137242173
1979	78.37923138623096
1980	77.71199124220314
1981	77.09530742947385
1982	77.0170132035589
1983	76.50491217860834
1984	76.56690710830738
1985	76.13846935408625
1986	75.81227013153523
1987	75.67961806009195
1988	69.22803854948845
1989	64.33879886691042
1990	71.24824684431978
1991	70.53824362606233
1992	74.01360544217687
1993	69.26751592356688
1994	66.30824372759857
1995	63.372093023255815
1996	62
1997	61.923847695390776
1998	61.23711340206186
1999	59.82532751091703
2000	57.85876993166287
2001	54.106280193236714
2002	54.43645083932853
2003	55.08274231678487
2004	55.73770491803278
2005	55.319148936170215
2006	55.847255369928405
2007	56.801909307875896
2008	55.33498759305211