Prescott (2004) argued that U.S. employees work 50% more than do German, French, and Italian employees because European employees face lower marginal tax rates. Assuming that workers in all four countries have the same tastes toward leisure and goods, must it necessarily be true that U.S. employees work longer hours? Use graphs to illustrate your answer, and explain why it is true or is not true. Does Prescott's evidence indicate anything about the relative sizes of the substitution and income effects? Why or why not?