Year	% of total
1970	2.1976711723062854
1971	2.5419254475568613
1972	3.1884545478780764
1973	3.784379311760708
1974	5.3440501743600235
1975	6.068597841916017
1976	5.510069067457785
1977	4.6994128554148755
1978	4.938019585614438
1979	5.837283587205425
1980	6.087518671041684
1981	7.0590405903824704
1982	8.113297197503337
1983	8.906494346497183
1984	8.953492722060387
1985	9.211140033608729
1986	6.809722170602474
1987	6.999201648112906
1988	6.763205239123766
1989	7.226021895008008
1990	1.8439297831538575
1991	1.7957020900794818
1992	1.7188188629352137
1993	1.6568914956011729
1994	1.609128145114102
1995	1.648191365227538
1996	1.7146178436501018
1997	1.5953589557650472
1998	1.7044633829264768
1999	1.5435660703981535
2000	1.340250756593169
2001	1.3637628722516002
2002	1.3589881593110873
2003	1.4319187711533454
2004	1.4998739601714142
2005	1.5518084066471163
2006	1.6846442855411463
2007	1.7562853362203776
2008	1.7447418738049714