In contrast to what many people in Britain and the United States believe, the true figures on growth (as best one can judge from official national accounts data) show that Britain and the United States have not grown any more rapidly since 1980 than Germany, France, Japan, Denmark, or Sweden. In other words, the reduction of top marginal income tax rates and the rise of top incomes do not seem to have stimulated productivity (contrary to the predictions of supply-side theory) or at any rate did not stimulate productivity enough to be statistically detectable at the macro level.