Year	% of total
1970	47.3467941354144
1971	47.681759235677376
1972	48.361834640026515
1973	47.541714170185514
1974	47.142223794808665
1975	47.21256157869199
1976	47.82142055450428
1977	46.979005637369546
1978	46.47654871884934
1979	45.84073544841905
1980	45.24025251408329
1981	44.06047893350839
1982	43.47130296735717
1983	42.53575173939437
1984	42.05276945469714
1985	40.670382233983055
1986	39.04677621810196
1987	38.15905051791838
1988	37.17868663605396
1989	36.03042143715641
1990	35.997559487492374
1991	36.45833333333333
1992	32.79352226720648
1993	27.958579881656803
1994	25.916453537936913
1995	23.377703826955074
1996	23.509933774834437
1997	22.530329289428074
1998	23.710407239819002
1999	25.915492957746476
2000	25.82781456953642
2001	25.502008032128515
2002	23.647932131495228
2003	24.008138351983725
2004	25.77873254564984
2005	26.013513513513516
2006	25.677267373380445
2007	26.02100350058343
2008	25.69360675512666