Fig. [ ]. Source: NBER Macrohistory Database.
There are two major declines clearly associated with major crises (of 1929-33 and 1937-38). But the contractions in 1951-2 and 1956-8 are not associated with major crises. In fact, there was not even a recession during the first period and the recession of 1957-8 lasted only for 8 months. In addition to this, if we look at the monthly registration data for 1958, it will be clear that most of the decline during that year took place starting from August when the recession was already over.