Year	% of total
1970	4.4611945078567095
1971	4.8604643270941095
1972	4.631237147976367
1973	5.4147927336699775
1974	4.732661283663226
1975	4.267895115564084
1976	3.922771573214752
1977	5.114248572744535
1978	4.0826092538154874
1979	3.968040020435108
1980	3.81841399915515
1981	3.713028969869193
1982	3.6990767682126404
1983	3.5673148148089235
1984	3.8281856675244823
1985	3.133193211220284
1986	2.778926770639571
1987	2.412370397361219
1988	2.774674696642819
1989	3.0105621870597563
1990	24.358974358974358
1991	25.581395348837212
1992	26.041666666666668
1993	29.347826086956523
1994	31.25
1995	33
1996	35.294117647058826
1997	39.39393939393939
1998	40.5940594059406
1999	42.30769230769231
2000	46.53465346534654
2001	44.761904761904766
2002	51.08695652173913
2003	47
2004	47
2005	51.06382978723404
2006	52.475247524752476
2007	56.730769230769226
2008	57.14285714285714