Year Percent
1950 3.018
1951 2.979
1952 2.902
1953 2.834
1954 2.778
1955 2.737
1956 2.715
1957 2.712
1958 2.731
1959 2.766
1960 2.813
1961 2.859
1962 2.892
1963 2.903
1964 2.893
1965 2.876
1966 2.861
1967 2.847
1968 2.83
1969 2.813
1970 2.794
1971 2.777
1972 2.77
1973 2.78
1974 2.804
1975 2.837
1976 2.868
1977 2.89
1978 2.897
1979 2.892
1980 2.884
1981 2.883
1982 2.883
1983 2.878
1984 2.872
1985 2.866
1986 2.866
1987 2.89
1988 2.949
1989 3.04
1990 3.143
1991 3.241
1992 3.328
1993 3.404
1994 3.467
1995 3.524
1996 3.576
1997 3.616
1998 3.636
1999 3.637
2000 3.629
2001 3.622
2002 3.624
2003 3.637
2004 3.661
2005 3.689
2006 3.713
2007 3.736
2008 3.76
2009 3.783
2010 3.806
2011 3.826
2012 3.839
2013 3.843
2014 3.839
2015 3.831
2016 3.822
2017 3.813
2018 3.807
2019 3.803
2020 3.799
2021 3.792
2022 3.783
2023 3.773
2024 3.761
2025 3.747
2026 3.731
2027 3.714
2028 3.695
2029 3.675
2030 3.653
2031 3.629
2032 3.604
2033 3.579
2034 3.552
2035 3.524
2036 3.495
2037 3.464
2038 3.433
2039 3.401
2040 3.368
2041 3.335
2042 3.3
2043 3.265
2044 3.229
2045 3.192
2046 3.155
2047 3.118
2048 3.08
2049 3.042
2050 3.004
2051 2.966
2052 2.927
2053 2.888
2054 2.849
2055 2.809
2056 2.77
2057 2.73
2058 2.691
2059 2.651
2060 2.612
2061 2.573
2062 2.533
2063 2.493
2064 2.453
2065 2.412
2066 2.371
2067 2.332
2068 2.294
2069 2.257
2070 2.221
2071 2.185
2072 2.149
2073 2.111
2074 2.073
2075 2.035
2076 1.997
2077 1.959
2078 1.923
2079 1.888
2080 1.854
2081 1.82
2082 1.786
2083 1.752
2084 1.719
2085 1.686
2086 1.654
2087 1.621
2088 1.59
2089 1.558
2090 1.527
2091 1.496
2092 1.465
2093 1.435
2094 1.406
2095 1.376
2096 1.347
2097 1.318
2098 1.29
2099 1.262