Year	% of total
1970	7.834941379886809
1971	7.934490097259109
1972	7.230903761532462
1973	7.067855160247383
1974	7.696475133170147
1975	7.35154651606041
1976	7.523946849353362
1977	7.586282523691777
1978	8.365365746895808
1979	8.703235937808577
1980	9.245960411597299
1981	9.440830424670324
1982	10.045199346368534
1983	10.42795116699754
1984	11.295246995287576
1985	11.452783385789665
1986	12.051596173441894
1987	12.43238031765438
1988	13.620183682189452
1989	13.901062652157293
1990	10.269248937175247
1991	10.87450312322544
1992	11.258955987717503
1993	11.8829468960359
1994	12.284423130130037
1995	12.743476662991549
1996	13.443967928398285
1997	13.90851617701748
1998	14.099290780141843
1999	13.66813833701251
2000	13.479566760717212
2001	13.505116959064328
2002	13.074330317544794
2003	12.333249433677322
2004	12.182361733931241
2005	12.127994694520435
2006	11.811665037471489
2007	11.623765581997732
2008	11.61100677716992