Coincidence?

Warren G. Harding, President March 4, 1921 to August 2, 1923, Republican; Calvin Coolidge, President August 2, 1923 to March 4, 1929, Republican; Herbert Hoover, President March 4, 1929 to March 4, 1933, Republican -> Great Depression: Aug 1929 – Mar 1933

Richard Nixon, President January 20, 1969 to August 9, 1974, Republican -> 1973–75 recession: Nov 1973 – Mar 1975

Jimmy Carter, President January 20, 1977 to January 20, 1981, Democratic; Ronald Reagan, President January 20, 1981 to January 20, 1989, Republican -> Early 1980s recession: July 1981 – Nov 1982

Ronald Reagan, President January 20, 1981 to January 20, 1989, Republican; George H. W. Bush, President January 20, 1989 to January 20, 1993, Republican -> Early 1990s recession: July 1990 – Mar 1991

George W. Bush, President January 20, 2001 to January 20, 2009, Republican -> Late 2000s recession: Dec 2007 - Dec 2009

Could it be coincidence that 7 of the 8 Presidents who preceded the five major economic collapses since the Great Depression were Republicans? (A Republican was in office at the start of ALL of them). Or could it be that gutting government services and putting all your faith in business is bad economic policy?