Year Percent
1950 2.403
1951 2.481
1952 2.611
1953 2.696
1954 2.749
1955 2.787
1956 2.82
1957 2.86
1958 2.912
1959 2.977
1960 3.049
1961 3.115
1962 3.16
1963 3.174
1964 3.16
1965 3.132
1966 3.107
1967 3.11
1968 3.156
1969 3.239
1970 3.338
1971 3.425
1972 3.485
1973 3.508
1974 3.498
1975 3.467
1976 3.432
1977 3.407
1978 3.399
1979 3.406
1980 3.416
1981 3.417
1982 3.389
1983 3.321
1984 3.219
1985 3.106
1986 3.003
1987 2.908
1988 2.817
1989 2.734
1990 2.654
1991 2.58
1992 2.54
1993 2.559
1994 2.628
1995 2.724
1996 2.817
1997 2.875
1998 2.88
1999 2.837
2000 2.775
2001 2.722
2002 2.688
2003 2.676
2004 2.685
2005 2.703
2006 2.72
2007 2.746
2008 2.791
2009 2.851
2010 2.917
2011 2.978
2012 3.021
2013 3.039
2014 3.032
2015 3.013
2016 2.994
2017 2.977
2018 2.962
2019 2.95
2020 2.937
2021 2.923
2022 2.907
2023 2.892
2024 2.878
2025 2.863
2026 2.848
2027 2.83
2028 2.808
2029 2.784
2030 2.758
2031 2.732
2032 2.706
2033 2.679
2034 2.653
2035 2.626
2036 2.599
2037 2.573
2038 2.548
2039 2.523
2040 2.498
2041 2.474
2042 2.45
2043 2.425
2044 2.401
2045 2.377
2046 2.352
2047 2.328
2048 2.304
2049 2.281
2050 2.258
2051 2.235
2052 2.211
2053 2.186
2054 2.16
2055 2.134
2056 2.107
2057 2.081
2058 2.056
2059 2.031
2060 2.006
2061 1.982
2062 1.958
2063 1.933
2064 1.909
2065 1.885
2066 1.861
2067 1.838
2068 1.815
2069 1.792
2070 1.77
2071 1.748
2072 1.725
2073 1.703
2074 1.681
2075 1.659
2076 1.637
2077 1.615
2078 1.593
2079 1.57
2080 1.548
2081 1.525
2082 1.503
2083 1.481
2084 1.458
2085 1.436
2086 1.414
2087 1.393
2088 1.371
2089 1.35
2090 1.328
2091 1.307
2092 1.286
2093 1.266
2094 1.245
2095 1.224
2096 1.204
2097 1.184
2098 1.164
2099 1.144