Year Percent
1950 2.418
1951 2.43
1952 2.421
1953 2.354
1954 2.255
1955 2.144
1956 2.04
1957 1.959
1958 1.912
1959 1.9
1960 1.916
1961 1.937
1962 1.938
1963 1.9
1964 1.83
1965 1.745
1966 1.678
1967 1.668
1968 1.744
1969 1.899
1970 2.098
1971 2.296
1972 2.469
1973 2.605
1974 2.705
1975 2.776
1976 2.837
1977 2.92
1978 3.045
1979 3.201
1980 3.373
1981 3.525
1982 3.584
1983 3.502
1984 3.299
1985 3.038
1986 2.792
1987 2.643
1988 2.643
1989 2.777
1990 2.98
1991 3.171
1992 3.277
1993 3.257
1994 3.128
1995 2.949
1996 2.794
1997 2.724
1998 2.774
1999 2.933
2000 3.139
2001 3.329
2002 3.469
2003 3.55
2004 3.575
2005 3.571
2006 3.565
2007 3.564
2008 3.565
2009 3.568
2010 3.57
2011 3.565
2012 3.546
2013 3.509
2014 3.457
2015 3.398
2016 3.341
2017 3.292
2018 3.255
2019 3.229
2020 3.209
2021 3.188
2022 3.165
2023 3.141
2024 3.116
2025 3.091
2026 3.066
2027 3.041
2028 3.015
2029 2.989
2030 2.961
2031 2.934
2032 2.906
2033 2.877
2034 2.847
2035 2.817
2036 2.787
2037 2.756
2038 2.724
2039 2.692
2040 2.659
2041 2.627
2042 2.594
2043 2.561
2044 2.528
2045 2.495
2046 2.463
2047 2.43
2048 2.398
2049 2.366
2050 2.334
2051 2.303
2052 2.272
2053 2.242
2054 2.211
2055 2.182
2056 2.152
2057 2.122
2058 2.093
2059 2.065
2060 2.037
2061 2.008
2062 1.98
2063 1.953
2064 1.925
2065 1.898
2066 1.87
2067 1.843
2068 1.815
2069 1.788
2070 1.76
2071 1.733
2072 1.706
2073 1.678
2074 1.652
2075 1.625
2076 1.598
2077 1.572
2078 1.546
2079 1.52
2080 1.495
2081 1.47
2082 1.444
2083 1.419
2084 1.394
2085 1.369
2086 1.344
2087 1.32
2088 1.296
2089 1.272
2090 1.249
2091 1.226
2092 1.203
2093 1.18
2094 1.157
2095 1.134
2096 1.112
2097 1.09
2098 1.068
2099 1.046