Year	% of total
1970	0.08330280750028123
1971	0.08951804990598344
1972	0.09445560006331648
1973	0.08759353403249023
1974	0.1406936697407955
1975	0.12630835429226414
1976	0.12226922722226438
1977	0.0972811743129575
1978	0.13286444967127337
1979	0.12000841362821278
1980	0.08876564052715454
1981	0.12306560336679925
1982	0.10176237116409456
1983	0.12001652609294126
1984	0.1292740060280651
1985	0.15770890731592568
1986	0.15908321627110886
1987	0.1504846320304295
1988	0.17181109522597418
1989	0.1476272889675983
1990	57.460317460317455
1991	57.902892561983464
1992	58.590978205778
1993	59.253731343283576
1994	53.60734586794928
1995	54.18994413407822
1996	52.53755582622818
1997	53.03514376996805
1998	51.57256536566881
1999	54.748822605965465
2000	52.23116313094367
2001	56.103379721669974
2002	58.63808322824716
2003	52.435312024353124
2004	55.03437120905782
2005	53.62838915470495
2006	53.8370253164557
2007	53.87323943661971
2008	52.80515542077331