Year	% of total
1970	42.26978404017319
1971	42.253076421399996
1972	42.342577269457905
1973	42.324221885007695
1974	40.34203716319127
1975	39.80472046305003
1976	38.45852488686829
1977	43.70037367726373
1978	44.234924833601774
1979	45.08091740568367
1980	45.38917201665408
1981	43.467288268207064
1982	43.58127905746495
1983	41.08320836407222
1984	41.8801396687438
1985	42.94282851193286
1986	46.54268106429353
1987	46.84456610986341
1988	50.244292185962195
1989	50.29307250526816
1990	91.5057915057915
1991	91.76954732510289
1992	91.26637554585153
1993	92.01877934272301
1994	91.4572864321608
1995	90.81081081081082
1996	91.75257731958763
1997	90.82125603864735
1998	90.82568807339449
1999	91.22807017543859
2000	91.9831223628692
2001	92.21311475409836
2002	92.43027888446214
2003	91.92307692307692
2004	92.13483146067416
2005	92.33576642335767
2006	92.04152249134948
2007	92.07920792079209
2008	92.11356466876973