Year Percent
1950 0.385
1951 0.501
1952 0.71
1953 0.877
1954 1.007
1955 1.106
1956 1.179
1957 1.232
1958 1.269
1959 1.294
1960 1.307
1961 1.304
1962 1.284
1963 1.244
1964 1.186
1965 1.115
1966 1.038
1967 0.969
1968 0.918
1969 0.884
1970 0.862
1971 0.839
1972 0.802
1973 0.741
1974 0.657
1975 0.563
1976 0.474
1977 0.408
1978 0.375
1979 0.376
1980 0.382
1981 0.376
1982 0.392
1983 0.464
1984 0.581
1985 0.736
1986 0.886
1987 0.908
1988 0.7
1989 0.275
1990 -0.278
1991 -0.836
1992 -1.271
1993 -1.484
1994 -1.457
1995 -1.29
1996 -1.112
1997 -0.983
1998 -0.93
1999 -0.963
2000 -1.037
2001 -1.096
2002 -1.134
2003 -1.163
2004 -1.18
2005 -1.191
2006 -1.201
2007 -1.213
2008 -1.225
2009 -1.236
2010 -1.246
2011 -1.254
2012 -1.251
2013 -1.231
2014 -1.193
2015 -1.144
2016 -1.091
2017 -1.041
2018 -0.999
2019 -0.966
2020 -0.94
2021 -0.913
2022 -0.884
2023 -0.853
2024 -0.82
2025 -0.786
2026 -0.753
2027 -0.73
2028 -0.721
2029 -0.726
2030 -0.74
2031 -0.757
2032 -0.768
2033 -0.771
2034 -0.761
2035 -0.747
2036 -0.733
2037 -0.721
2038 -0.709
2039 -0.699
2040 -0.689
2041 -0.679
2042 -0.671
2043 -0.666
2044 -0.666
2045 -0.667
2046 -0.67
2047 -0.672
2048 -0.675
2049 -0.678
2050 -0.681
2051 -0.685
2052 -0.689
2053 -0.692
2054 -0.695
2055 -0.699
2056 -0.702
2057 -0.704
2058 -0.705
2059 -0.705
2060 -0.704
2061 -0.702
2062 -0.699
2063 -0.695
2064 -0.691
2065 -0.684
2066 -0.678
2067 -0.67
2068 -0.66
2069 -0.65
2070 -0.639
2071 -0.626
2072 -0.613
2073 -0.6
2074 -0.586
2075 -0.571
2076 -0.557
2077 -0.541
2078 -0.526
2079 -0.51
2080 -0.495
2081 -0.48
2082 -0.466
2083 -0.451
2084 -0.438
2085 -0.427
2086 -0.415
2087 -0.405
2088 -0.398
2089 -0.393
2090 -0.389
2091 -0.387
2092 -0.387
2093 -0.387
2094 -0.389
2095 -0.392
2096 -0.397
2097 -0.403
2098 -0.412
2099 -0.424