Year	% of total
1970	70.8791697531537
1971	84.12991755890299
1972	80.82797942039818
1973	77.21571912704425
1974	91.78792687264283
1975	92.57470415328206
1976	93.93394352659105
1977	88.19566466087934
1978	85.36936498521386
1979	87.89391510137928
1980	86.6251406876178
1981	87.08480595522198
1982	87.45299989651366
1983	74.61160814395306
1984	86.43156287941983
1985	89.8530522026382
1986	86.15276390341874
1987	80.24750085948425
1988	86.18076120702861
1989	93.534185985601
1990	99.29078014184397
1991	99.3006993006993
1992	99.21182266009852
1993	99.31906614785993
1994	99.23224568138195
1995	99.33649289099526
1996	99.26402943882245
1997	99.19571045576407
1998	99.21739130434783
1999	99.15397631133672
2000	99.17559769167353
2001	99.01800327332242
2002	98.9430894308943
2003	98.86914378029078
2004	98.7169206094627
2005	98.64541832669322
2006	98.59038142620233
2007	98.53068280034573
2008	98.5546522131888