Annual % of total
1960 82.95454545454544
1961 83.60655737704919
1962 84.72400513478819
1963 84.50363196125907
1964 85.6341189674523
1965 84.64088397790054
1966 84.64646464646465
1967 85.72895277207392
1968 87.41328047571852
1969 85.08845829823083
1970 82.91550603528319
1971 85.78296703296702
1972 85.0832266325224
1973 87.93456032719837
1974 87.6267748478702
1975 86.77309007981756
1976 85.87672052663076
1977 87.5657894736842
1978 87.67650834403082
1979 82.54913639070877
1980 87.77448071216617
1981 81.00461893764435
1982 86.02279544091182
1983 89.77955911823648
1984 91.15964638585544
1985 93.80974055530268
1986 94.18714555765595
1987 94.33962264150945
1988 94.11201531833413
1989 94.39890710382514
1990 138.197615658363
1991 114.07286931818182
1992 136.91178062678063
1993 95.77508228460795
1994 94.81488908606921
1995 85.05785714285715
1996 80.84540368271954
1997 84.86615623062616
1998 89.00091076923077
1999 85.74277157956548
2000 85.15770899808551
2001 84.23895796329188
2002 83.59627672209025
2003 90.40071223434806
2004 78.87741610738254
2005 77.60543402777778
2006 75.73495995070856
2007 73.02324916943522
2008 78.27256698821007
2009 81.36992700729927
2010 78.50330459770116
2011 80.61167138810198
2012 82.44502981260648
2013 82.49172117039588
2014 82.97065356856456
2015 77.82716081330868
2016 77.16391226177633