Year	% of total
1970	27.5264349079406
1971	34.40089366666505
1972	33.92258210632734
1973	30.235021143645792
1974	30.424470276706305
1975	30.789674398699013
1976	32.068460207390295
1977	32.47716305817689
1978	31.91533913859097
1979	28.88365592233473
1980	30.57492321643548
1981	32.15251515377792
1982	30.848414573178367
1983	30.913358850182384
1984	33.909049296938186
1985	34.1841400067445
1986	35.352332491917
1987	32.21375460738241
1988	37.131158569324604
1989	36.12865723686218
1990	56.00000000000001
1991	56.64739884393064
1992	57.30994152046783
1993	58.57988165680473
1994	59.63855421686747
1995	58.57988165680473
1996	35.96491228070175
1997	36.666666666666664
1998	36.8
1999	36.434108527131784
2000	30.89430894308943
2001	33.83458646616541
2002	42.857142857142854
2003	53.398058252427184
2004	54.12844036697248
2005	57.377049180327866
2006	55.55555555555556
2007	50.76335877862596
2008	48.72727272727273