Year Percent
1950 0.086
1951 0.207
1952 0.422
1953 0.588
1954 0.716
1955 0.819
1956 0.909
1957 0.996
1958 1.088
1959 1.185
1960 1.282
1961 1.363
1962 1.408
1963 1.403
1964 1.351
1965 1.272
1966 1.187
1967 1.118
1968 1.076
1969 1.062
1970 1.061
1971 1.058
1972 1.04
1973 1.005
1974 0.951
1975 0.889
1976 0.83
1977 0.783
1978 0.756
1979 0.748
1980 0.743
1981 0.729
1982 0.724
1983 0.746
1984 0.79
1985 0.85
1986 0.903
1987 0.888
1988 0.756
1989 0.51
1990 0.202
1991 -0.107
1992 -0.364
1993 -0.531
1994 -0.604
1995 -0.626
1996 -0.648
1997 -0.679
1998 -0.714
1999 -0.755
2000 -0.793
2001 -0.822
2002 -0.86
2003 -0.932
2004 -1.037
2005 -1.159
2006 -1.274
2007 -1.366
2008 -1.421
2009 -1.433
2010 -1.423
2011 -1.405
2012 -1.358
2013 -1.257
2014 -1.103
2015 -0.913
2016 -0.715
2017 -0.549
2018 -0.449
2019 -0.419
2020 -0.429
2021 -0.444
2022 -0.455
2023 -0.464
2024 -0.468
2025 -0.473
2026 -0.486
2027 -0.503
2028 -0.52
2029 -0.535
2030 -0.551
2031 -0.568
2032 -0.584
2033 -0.597
2034 -0.606
2035 -0.613
2036 -0.62
2037 -0.625
2038 -0.627
2039 -0.627
2040 -0.625
2041 -0.622
2042 -0.619
2043 -0.615
2044 -0.613
2045 -0.61
2046 -0.607
2047 -0.603
2048 -0.599
2049 -0.595
2050 -0.59
2051 -0.586
2052 -0.581
2053 -0.577
2054 -0.573
2055 -0.57
2056 -0.567
2057 -0.564
2058 -0.561
2059 -0.559
2060 -0.557
2061 -0.555
2062 -0.553
2063 -0.551
2064 -0.549
2065 -0.546
2066 -0.543
2067 -0.539
2068 -0.534
2069 -0.529
2070 -0.524
2071 -0.517
2072 -0.511
2073 -0.504
2074 -0.497
2075 -0.489
2076 -0.481
2077 -0.473
2078 -0.465
2079 -0.457
2080 -0.448
2081 -0.44
2082 -0.431
2083 -0.423
2084 -0.413
2085 -0.404
2086 -0.396
2087 -0.387
2088 -0.378
2089 -0.369
2090 -0.361
2091 -0.353
2092 -0.346
2093 -0.34
2094 -0.335
2095 -0.331
2096 -0.328
2097 -0.326
2098 -0.326
2099 -0.327