Year	% of total
1970	75.35098488291786
1971	75.96743474793246
1972	73.7714681962981
1973	72.79222419411178
1974	73.6403452451731
1975	76.08440922728397
1976	75.74538972593692
1977	73.61694306269175
1978	72.50028584186927
1979	71.37537370053259
1980	70.36638087405802
1981	67.93709417862436
1982	67.58284326475686
1983	65.1179611136635
1984	64.72606689265572
1985	67.12019608318845
1986	65.76870795122433
1987	63.75022235621665
1988	64.8399551007323
1989	64.6065668568005
1990	66.2330171750833
1991	65.77207062600321
1992	64.54211509956822
1993	64.7500493973523
1994	66.37461834594451
1995	65.35960855285207
1996	64.30933783688691
1997	63.150960404964984
1998	64.20995004448095
1999	69.01928339591421
2000	70.11871383403926
2001	71.77983949001081
2002	71.16707543219476
2003	63.32310597120604
2004	68.29268292682927
2005	62.89596273291925
2006	67.06566578751605
2007	65.11081958157841
2008	60.27386602349646