It might be zero for some people, but it's actually-- it is--the standard rate for people who have not negligible income is 15%.

对某些收益较少的人来说税率是零,但实际上...,对于大部分投资获利的人来说,标准税率是15%

耶鲁公开课 - 金融市场课程节选

It obviously applies in Economics, but it also applies in politics, and in fact, this class will count as a Political Science class if you're a Political Science major.

显然适用于经济学,但也适用于政治学,实际上,对政治专业的同学来说,它也算作政治课

耶鲁公开课 - 博弈论课程节选