Year,Value,Contiguous U.S. (Lower 48),Precip,May-Jun,(in.)
1940,5.319
1941,6.12
1942,6.362
1943,6.276
1944,5.873
1945,6.612
1946,6.744
1947,7.159
1948,5.948
1949,6.229
1950,5.676
1951,5.982
1952,4.752
1953,5.858
1954,5.077
1955,5.351
1956,4.624
1957,7.685
1958,5.406
1959,5.801
1960,5.604
1961,5.655
1962,5.473
1963,5.167
1964,4.913
1965,5.458
1966,3.991
1967,6.27
1968,6.047
1969,5.511
1970,4.878
1971,4.915
1972,5.83
1973,6.005
1974,5.726
1975,6.246
1976,5.785
1977,5.255
1978,6.258
1979,5.91
1980,6.0
1981,7.232
1982,7.323
1983,6.939
1984,6.405
1985,5.55
1986,6.463
1987,6.301
1988,4.256
1989,7.499
1990,6.568
1991,6.686
1992,6.048
1993,7.003
1994,5.683
1995,7.693
1996,6.462
1997,6.572
1998,6.403
1999,6.29
2000,6.255
2001,5.787
2002,5.376
2003,6.819
2004,6.633
2005,5.869
2006,4.619
2007,5.428
2008,5.935
2009,6.388
2010,6.551
2011,6.021
2012,4.492
2013,6.349
2014,6.107
2015,7.276
2016,5.396
2017,6.503
2018,6.123
2019,7.912
2020,5.728
2021,6.181
2022,5.664
2023,5.439
2024,6.393
2025,6.988