Year	% of total
1970	0.99073927480273
1971	1.1644339702710604
1972	1.1704804904164123
1973	1.1820485546854504
1974	1.1456858503436989
1975	1.4895575612881986
1976	1.5874105027404999
1977	1.3817966678849558
1978	1.409482426541408
1979	1.3091096704796246
1980	1.399908907397046
1981	1.774873891092696
1982	1.948413031066352
1983	2.1010777280304573
1984	2.308339702829041
1985	2.3932607757309947
1986	2.279693895684949
1987	2.2397093784724014
1988	2.4311037580406336
1989	2.364259428517479
1990	3.50109409190372
1991	3.411513859275053
1992	3.470715835140998
1993	3.3632286995515694
1994	3.3783783783783785
1995	3.611738148984198
1996	3.953488372093023
1997	4.25531914893617
1998	4.157549234135667
1999	4.319654427645788
2000	4.133858267716536
2001	4.713114754098361
2002	5.5045871559633035
2003	5.603448275862069
2004	5.613305613305614
2005	5.566218809980806
2006	5.0966608084358525
2007	5.420560747663552
2008	6.401766004415011