As of the fourth quarter of 2009, the unemployment rate was about 1.5 percentage points higher than the level implied by Okun’s law. Panel B of Figure 1.10 confirms that unemployment has responded more strongly to the decline in output in the United States during the 2008-09 recession than in past recessions, even as the unemployment response has been weaker than in the past in the large majority of OECD countries. Okun (1962) highlighted two such factors, namely, procyclical variations in labour force participation and labour productivity.