Recessions since 1947

Seems to be two ways they measured GDP. Percent changed based on current dollars and percent changed based on chained 2005 dollars.

Recessions based on current dollars:
1949 q1-q2
1953 q3-1954 q1
1957 q4-1958 q1
2008 q3-2009 q2
4 periods of recession

Recessions based on 2005 chained dollars:
1947 q2-q3
1949 q1-q2
1953 q3-1954 q1
1957 q4-1958 q1
1974 q3-1975 q1
1980 q2-q3
1981 q4-1982 q1
1990 q4-1991 q1
2001 q3-q4
2008 q3-2009 q2
10 periods of recession