From the passage note down the years when global recession happened. List the results in comma separated format.

Context: The International Monetary Fund defines a global recession as "a decline in annual per‑capita real World GDP, 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".According to this definition, since World War II there were only four global recessions, all of them only lasting a year. The 2009 global recession, also known as the Great Recession, was by far the worst of the four postwar recessions, both in terms of the number of countries affected and the decline in real World GDP per capita.

Answer: 1975, 1982, 1991, 2009