Year,Value,Contiguous U.S. (Lower 48),Precip,Apr,(in.)
1940,68.252
1941,58.305
1942,45.026
1943,31.77
1944,62.519
1945,64.207
1946,15.08
1947,58.715
1948,43.6
1949,28.631
1950,33.311
1951,45.045
1952,39.437
1953,58.108
1954,38.204
1955,43.299
1956,32.276
1957,65.314
1958,60.422
1959,23.114
1960,34.62
1961,35.98
1962,20.762
1963,35.076
1964,61.384
1965,50.39
1966,30.76
1967,47.804
1968,35.021
1969,38.066
1970,47.54
1971,23.586
1972,33.123
1973,63.143
1974,42.318
1975,50.168
1976,45.781
1977,31.709
1978,44.94
1979,50.315
1980,39.948
1981,30.773
1982,42.147
1983,63.739
1984,68.584
1985,29.204
1986,45.839
1987,14.851
1988,42.626
1989,21.0
1990,42.469
1991,61.187
1992,30.611
1993,56.886
1994,51.111
1995,63.089
1996,38.67
1997,64.519
1998,44.894
1999,56.259
2000,33.269
2001,40.573
2002,31.896
2003,42.779
2004,40.652
2005,49.451
2006,40.015
2007,35.341
2008,31.571
2009,49.757
2010,45.54
2011,61.716
2012,34.048
2013,47.117
2014,41.79
2015,37.582
2016,56.371
2017,65.572
2018,40.847
2019,73.397
2020,34.778
2021,22.988
2022,41.271
2023,33.125
2024,49.596
2025,41.245