Year Percent
1950 2.876
1951 2.802
1952 2.682
1953 2.613
1954 2.588
1955 2.604
1956 2.656
1957 2.739
1958 2.847
1959 2.972
1960 3.102
1961 3.223
1962 3.318
1963 3.378
1964 3.401
1965 3.409
1966 3.414
1967 3.381
1968 3.282
1969 3.13
1970 2.954
1971 2.791
1972 2.684
1973 2.658
1974 2.708
1975 2.797
1976 2.888
1977 2.956
1978 2.993
1979 3.002
1980 2.995
1981 2.992
1982 3.02
1983 3.096
1984 3.212
1985 3.343
1986 3.458
1987 3.528
1988 3.538
1989 3.492
1990 3.425
1991 3.365
1992 3.311
1993 3.255
1994 3.202
1995 3.15
1996 3.103
1997 3.086
1998 3.118
1999 3.194
2000 3.288
2001 3.375
2002 3.439
2003 3.474
2004 3.48
2005 3.472
2006 3.462
2007 3.454
2008 3.444
2009 3.434
2010 3.422
2011 3.407
2012 3.388
2013 3.364
2014 3.336
2015 3.306
2016 3.276
2017 3.246
2018 3.218
2019 3.191
2020 3.164
2021 3.137
2022 3.109
2023 3.081
2024 3.053
2025 3.025
2026 2.997
2027 2.967
2028 2.936
2029 2.904
2030 2.872
2031 2.838
2032 2.805
2033 2.77
2034 2.734
2035 2.698
2036 2.661
2037 2.625
2038 2.589
2039 2.553
2040 2.518
2041 2.482
2042 2.447
2043 2.413
2044 2.378
2045 2.344
2046 2.31
2047 2.276
2048 2.243
2049 2.209
2050 2.176
2051 2.143
2052 2.11
2053 2.077
2054 2.044
2055 2.01
2056 1.977
2057 1.943
2058 1.91
2059 1.877
2060 1.845
2061 1.812
2062 1.78
2063 1.748
2064 1.717
2065 1.686
2066 1.655
2067 1.625
2068 1.595
2069 1.565
2070 1.535
2071 1.505
2072 1.476
2073 1.446
2074 1.417
2075 1.388
2076 1.36
2077 1.331
2078 1.302
2079 1.274
2080 1.246
2081 1.218
2082 1.19
2083 1.162
2084 1.134
2085 1.107
2086 1.08
2087 1.053
2088 1.027
2089 1
2090 0.975
2091 0.949
2092 0.923
2093 0.898
2094 0.873
2095 0.847
2096 0.822
2097 0.798
2098 0.773
2099 0.749