| Year | Teams | State | |
| 1919 | 6 | Minnesota | |
| 1920 | 15 | Missouri | |
| 1921 | 13 | Maryland | |
| 1922 | * | Maryland | |
| 1923 | 20 | Illinois | |
| 1924 | 20 | Iowa | |
| 1925 | 23 | Maryland | |
| 1926 | 21 | Iowa | |
| 1927 | 26 | Nebraska | |
| 1928 | 26 | Oklahoma | |
| 1929 | 27 | Oklahoma | |
| 1930 | 25 | Maryland | |
| 1931 | 24 | Oklahoma | |
| 1932 | 13 | Wisconsin | |
| 1933 | 12 | Nebraska | |
| 1934 | 13 | Iowa | |
| 1935 | 20 | Iowa | |
| 1936 | 20 | Oklahoma | |
| 1937 | 25 | Nebraska | |
| 1938 | 24 | Illinois | |
| 1939 | 17 | Maryland | |
| 1940 | 28 | Michigan | |
| 1941 | * | Minnesota | |
| 1942 | 11 | Kansas | |
| 1943-45 | | No contest – World War II | |
| 1946 | 10 | Maryland | |
| 1947 | 14 | Maryland | |
| 1948 | 17 | Michigan | |
| 1949 | 18 | Maryland | |
| 1950 | 21 | Maryland | |
| 1951 | 27 | Florida | |
| 1952 | 30 | Michigan | |
| 1953 | 31 | Maryland | |
| 1954 | 32 | Maryland | |
| 1955 | 30 | Maryland | |
| 1956 | 30 | Washington | |
| 1957 | 32 | Maryland | |
| 1958 | 32 | Nebraska | |
| 1959 | 33 | Maryland | |
| 1960 | 33 | Maryland | |
| 1961 | 34 | Maryland | |
| 1962 | 34 | Maryland | |
| 1963 | 34 | New York | |
| 1964 | 34 | Kansas | |
| 1965 | 33 | Maryland | |
| 1966 | 34 | Maryland | |
| 1967 | 34 | North Carolina | |
| 1968 | 36 | New York | |
| 1969 | 33 | Virginia | |
| 1970 | 32 | Massachusetts | |
| 1971 | 33 | Wisconsin | |
| 1972 | 34 | Maryland | |
| 1973 | 33 | Wisconsin | |
| 1974 | 36 | Maryland | |
| 1975 | 35 | Kentucky | |
| 1976 | 34 | Maryland | |
| 1977 | 36 | Virginia | |
| 1978 | 38 | Maryland | |
| 1979 | 36 | North Carolina | |
| 1980 | 37 | Michigan | |
| 1981 | 37 | Kentucky | |
| 1982 | 37 | Ohio | |
| 1983 | 36 | Wisconsin | |
| 1984 | 36 | New York | |
| 1985 | 35 | Maryland | |
| 1986 | 37 | Kentucky | |
| 1987 | 38 | Minnesota | |
| 1988 | 36 | Pennsylvania | |
| 1989 | 36 | Maryland | |
| 1990 | 36 | New York | |
| 1991 | 36 | Minnesota | |
| 1992 | 37 | Maryland | |
| 1993 | 34 | Florida | |
| 1994 | 38 | Virginia | |
| 1995 | 32 | Maryland | |
| 1996 | 32 | Kentucky | |
| 1997 | 34 | Texas | |
| 1998 | 33 | New York | |
| 1999 | 32 | Ohio | |
| 2000 | 31 | Wisconsin | |
| 2001 | 31 | Wisconsin | |
| 2002 | 28 | Wisconsin | |
| 2003 | 31 | Minnesota | |
| 2004 | 29 | Wisconsin | |
| 2005 | 28 | Wisconsin | |
| 2006 | 31 | Maryland | |
| 2007 | 29 | Minnesota | |
| 2008 | 27 | Pennsylvania | |
| 2009 | 26 | Maryland | |
| 2010 | 27 | Maryland | |
| 2011 | 28 | New York | |
| 2012 | 31 | Michigan | |
| 2013 | 25 | Maryland | |
| 2014 | 23 | Michigan | |
| 2015 | 26 | Wisconsin |
