That's a fair point. I was including the smaller recessions as well: there is a boom and a bust within a ten year span.

That the IMF changed the definition of a global recession is a little weird, but they know better than I do.

From wikipedia:

According to the International Monetary Fund (IMF), "Global recessions seem to occur over a cycle lasting between eight and 10 years."[48] The IMF takes many factors into account when defining a global recession. Until April 2009, IMF several times communicated to the press, that a global annual real GDP growth of 3.0 percent or less in their view was "...equivalent to a global recession."[49][50] By this measure, six periods since 1970 qualify: 1974–1975,[51] 1980–1983,[51] 1990–1993,[51][52] 1998,[51][52] 2001–2002,[51][52] and 2008–2009.[53] During what IMF in April 2002 termed the past three global recessions of the last three decades, global per capita output growth was zero or negative, and IMF argued—at that time—that because of the opposite being found for 2001, the economic state in this year by itself did not qualify as a global recession.[48]

In April 2009, IMF had changed their Global recession definition to:

    A decline in annual per‑capita real World GDP (purchasing power parity weighted), backed up by a decline or worsening for one or more of the seven other global macroeconomic indicators: Industrial production, trade, capital flows, oil consumption, unemployment rate, per‑capita investment, and per‑capita consumption.[54][55]

By this new definition, a total of four global recessions took place since World War II: 1975, 1982, 1991 and 2009. All of them only lasted one year, although the third would have lasted three years (1991–93) if IMF as criteria had used the normal exchange rate weighted per‑capita real World GDP rather than the purchase power parity weighted per‑capita real World GDP.[54][55]

[0] https://en.wikipedia.org/wiki/Recession#Global