Year	% of total
1970	1.276364454041498
1971	1.2148265839491879
1972	1.2824018530479104
1973	1.3646012000844756
1974	1.4613040509623867
1975	1.6843130636726822
1976	1.7883841696626637
1977	1.7970529528504933
1978	1.8530321285140559
1979	1.917338116117406
1980	1.9799679903715037
1981	2.08048445690134
1982	2.0837340266440534
1983	2.0151471458691046
1984	1.9800619180972867
1985	1.9950305052744297
1986	2.0222887551359743
1987	1.9901472551731025
1988	2.153071701734009
1989	2.1944273609322003
1990	2.1052631578947367
1991	2.0618556701030926
1992	1.9607843137254901
1993	2.9787234042553195
1994	3.587443946188341
1995	4.464285714285714
1996	4.166666666666666
1997	3.9647577092511015
1998	3.4782608695652173
1999	3.375527426160337
2000	2.941176470588235
2001	2.7237354085603114
2002	2.6022304832713754
2003	2.527075812274368
2004	2.0689655172413794
2005	2.0338983050847457
2006	1.948051948051948
2007	1.935483870967742
2008	1.82370820668693