Year,Value,Contiguous U.S. (Lower 48),Precip,Mar,(in.)
1940,2.551
1941,2.076
1942,2.578
1943,2.931
1944,2.988
1945,3.278
1946,3.037
1947,2.448
1948,3.457
1949,3.048
1950,2.793
1951,2.887
1952,3.222
1953,2.904
1954,2.512
1955,2.21
1956,2.13
1957,2.859
1958,2.926
1959,2.545
1960,2.43
1961,3.364
1962,2.386
1963,2.671
1964,3.107
1965,2.307
1966,1.831
1967,2.143
1968,2.433
1969,2.049
1970,2.785
1971,2.272
1972,2.26
1973,4.372
1974,2.811
1975,3.63
1976,2.78
1977,3.397
1978,2.436
1979,3.069
1980,3.715
1981,2.547
1982,3.012
1983,4.033
1984,3.188
1985,2.982
1986,2.281
1987,3.042
1988,2.433
1989,3.145
1990,2.966
1991,3.58
1992,2.675
1993,3.209
1994,2.561
1995,3.19
1996,2.481
1997,2.657
1998,3.42
1999,2.442
2000,2.715
2001,2.703
2002,2.807
2003,2.632
2004,2.168
2005,2.573
2006,2.566
2007,2.569
2008,2.774
2009,2.9
2010,2.488
2011,3.056
2012,2.977
2013,1.97
2014,2.609
2015,2.257
2016,3.185
2017,2.893
2018,2.833
2019,2.516
2020,3.187
2021,2.725
2022,2.526
2023,3.191
2024,3.132
2025,2.707