Year Percent
1950 2.261
1951 2.316
1952 2.42
1953 2.511
1954 2.591
1955 2.659
1956 2.717
1957 2.766
1958 2.806
1959 2.839
1960 2.866
1961 2.887
1962 2.903
1963 2.915
1964 2.923
1965 2.929
1966 2.931
1967 2.931
1968 2.93
1969 2.927
1970 2.923
1971 2.917
1972 2.911
1973 2.905
1974 2.898
1975 2.889
1976 2.879
1977 2.872
1978 2.871
1979 2.873
1980 2.879
1981 2.883
1982 2.878
1983 2.861
1984 2.831
1985 2.801
1986 2.776
1987 2.754
1988 2.731
1989 2.711
1990 2.689
1991 2.669
1992 2.675
1993 2.725
1994 2.812
1995 2.917
1996 3.013
1997 3.073
1998 3.083
1999 3.046
2000 2.989
2001 2.936
2002 2.896
2003 2.867
2004 2.852
2005 2.84
2006 2.824
2007 2.82
2008 2.84
2009 2.88
2010 2.927
2011 2.967
2012 2.982
2013 2.961
2014 2.906
2015 2.835
2016 2.766
2017 2.705
2018 2.654
2019 2.614
2020 2.579
2021 2.543
2022 2.505
2023 2.466
2024 2.427
2025 2.388
2026 2.35
2027 2.314
2028 2.281
2029 2.25
2030 2.221
2031 2.192
2032 2.164
2033 2.136
2034 2.108
2035 2.08
2036 2.053
2037 2.026
2038 1.998
2039 1.971
2040 1.944
2041 1.917
2042 1.89
2043 1.862
2044 1.835
2045 1.808
2046 1.781
2047 1.753
2048 1.726
2049 1.698
2050 1.671
2051 1.643
2052 1.616
2053 1.59
2054 1.564
2055 1.538
2056 1.513
2057 1.488
2058 1.463
2059 1.439
2060 1.415
2061 1.391
2062 1.367
2063 1.344
2064 1.321
2065 1.298
2066 1.276
2067 1.254
2068 1.231
2069 1.21
2070 1.188
2071 1.166
2072 1.145
2073 1.124
2074 1.103
2075 1.082
2076 1.062
2077 1.041
2078 1.021
2079 1.001
2080 0.982
2081 0.962
2082 0.942
2083 0.922
2084 0.901
2085 0.879
2086 0.858
2087 0.837
2088 0.817
2089 0.797
2090 0.778
2091 0.76
2092 0.741
2093 0.722
2094 0.704
2095 0.685
2096 0.667
2097 0.649
2098 0.632
2099 0.615