Year Percent
1950 1.518
1951 1.374
1952 1.107
1953 0.882
1954 0.695
1955 0.544
1956 0.429
1957 0.349
1958 0.301
1959 0.282
1960 0.287
1961 0.307
1962 0.331
1963 0.349
1964 0.36
1965 0.37
1966 0.387
1967 0.398
1968 0.392
1969 0.37
1970 0.332
1971 0.289
1972 0.267
1973 0.288
1974 0.349
1975 0.436
1976 0.519
1977 0.542
1978 0.463
1979 0.284
1980 0.051
1981 -0.179
1982 -0.361
1983 -0.464
1984 -0.484
1985 -0.461
1986 -0.436
1987 -0.404
1988 -0.349
1989 -0.276
1990 -0.186
1991 -0.089
1992 -0.019
1993 -0.005
1994 -0.047
1995 -0.121
1996 -0.198
1997 -0.256
1998 -0.287
1999 -0.288
2000 -0.274
2001 -0.261
2002 -0.256
2003 -0.26
2004 -0.274
2005 -0.293
2006 -0.311
2007 -0.323
2008 -0.325
2009 -0.318
2010 -0.306
2011 -0.294
2012 -0.286
2013 -0.286
2014 -0.294
2015 -0.307
2016 -0.32
2017 -0.331
2018 -0.342
2019 -0.35
2020 -0.358
2021 -0.367
2022 -0.376
2023 -0.386
2024 -0.397
2025 -0.407
2026 -0.418
2027 -0.429
2028 -0.442
2029 -0.457
2030 -0.472
2031 -0.487
2032 -0.501
2033 -0.514
2034 -0.525
2035 -0.536
2036 -0.546
2037 -0.554
2038 -0.56
2039 -0.564
2040 -0.567
2041 -0.568
2042 -0.569
2043 -0.568
2044 -0.566
2045 -0.564
2046 -0.561
2047 -0.558
2048 -0.556
2049 -0.555
2050 -0.554
2051 -0.553
2052 -0.553
2053 -0.554
2054 -0.558
2055 -0.562
2056 -0.566
2057 -0.571
2058 -0.577
2059 -0.583
2060 -0.589
2061 -0.595
2062 -0.6
2063 -0.604
2064 -0.608
2065 -0.61
2066 -0.611
2067 -0.611
2068 -0.609
2069 -0.604
2070 -0.598
2071 -0.59
2072 -0.582
2073 -0.573
2074 -0.564
2075 -0.554
2076 -0.544
2077 -0.534
2078 -0.524
2079 -0.515
2080 -0.506
2081 -0.497
2082 -0.489
2083 -0.481
2084 -0.473
2085 -0.466
2086 -0.46
2087 -0.453
2088 -0.446
2089 -0.439
2090 -0.431
2091 -0.424
2092 -0.418
2093 -0.412
2094 -0.406
2095 -0.401
2096 -0.397
2097 -0.392
2098 -0.388
2099 -0.384