Result of the principal factor analysis for upper-middle-income economies.

†Refer to Table S2 for details and units. ‡Extraction method was Principal component analysis. §Rotation method was Quartimax with Kaizer Normalization.†详见补充表S2（Table S2）以获取详细信息及单位。 ‡提取方法为主成分分析（Principal component analysis）。 §旋转方法为结合凯泽标准化（Kaiser Normalization）的四次极大方差旋转（Quartimax）。