1955-80年间,英、法、l52J、加四国jDqY债实际利tBTb的均值为1.67%,远低于1980-2000年间4.86%的水平(图2)Dvyv
BillandMelindaGatessharetheir2018AnnualLetter,“The10ToughestQuestionsWeGet.”Inthisyear’sletter,the10thonethatthey’vewritten.