Year Percent
1950 0.966
1951 0.942
1952 0.894
1953 0.85
1954 0.806
1955 0.762
1956 0.717
1957 0.668
1958 0.617
1959 0.562
1960 0.509
1961 0.461
1962 0.424
1963 0.405
1964 0.403
1965 0.416
1966 0.436
1967 0.465
1968 0.501
1969 0.546
1970 0.59
1971 0.631
1972 0.698
1973 0.817
1974 0.979
1975 1.167
1976 1.344
1977 1.444
1978 1.418
1979 1.274
1980 1.07
1981 0.873
1982 0.712
1983 0.6
1984 0.542
1985 0.506
1986 0.467
1987 0.459
1988 0.523
1989 0.652
1990 0.818
1991 0.98
1992 1.088
1993 1.104
1994 1.03
1995 0.909
1996 0.79
1997 0.682
1998 0.586
1999 0.504
2000 0.423
2001 0.334
2002 0.264
2003 0.239
2004 0.256
2005 0.302
2006 0.351
2007 0.355
2008 0.276
2009 0.115
2010 -0.092
2011 -0.297
2012 -0.446
2013 -0.501
2014 -0.459
2015 -0.361
2016 -0.259
2017 -0.186
2018 -0.158
2019 -0.178
2020 -0.222
2021 -0.261
2022 -0.288
2023 -0.303
2024 -0.305
2025 -0.301
2026 -0.298
2027 -0.297
2028 -0.296
2029 -0.295
2030 -0.295
2031 -0.295
2032 -0.296
2033 -0.298
2034 -0.301
2035 -0.306
2036 -0.312
2037 -0.32
2038 -0.33
2039 -0.343
2040 -0.357
2041 -0.373
2042 -0.391
2043 -0.411
2044 -0.433
2045 -0.457
2046 -0.481
2047 -0.506
2048 -0.531
2049 -0.555
2050 -0.579
2051 -0.603
2052 -0.625
2053 -0.647
2054 -0.666
2055 -0.683
2056 -0.699
2057 -0.714
2058 -0.725
2059 -0.733
2060 -0.738
2061 -0.742
2062 -0.744
2063 -0.744
2064 -0.743
2065 -0.74
2066 -0.735
2067 -0.729
2068 -0.719
2069 -0.707
2070 -0.693
2071 -0.678
2072 -0.662
2073 -0.646
2074 -0.63
2075 -0.615
2076 -0.598
2077 -0.582
2078 -0.567
2079 -0.552
2080 -0.537
2081 -0.523
2082 -0.51
2083 -0.499
2084 -0.49
2085 -0.481
2086 -0.473
2087 -0.467
2088 -0.463
2089 -0.461
2090 -0.46
2091 -0.46
2092 -0.46
2093 -0.459
2094 -0.457
2095 -0.455
2096 -0.452
2097 -0.449
2098 -0.445
2099 -0.441