گزینههای پاسخ: Missing; Unknown, Not asked in survey, Not applicable, No answer, Don't know, Argentina [1991], Brazil [1991], Belarus [1990], Chile [1990], China [1990], Czech Republic [1991], India [1990], Japan [1990], South Korea [1990], Mexico [1990], Nigeria [1990], Poland [1989], Russian Federation [1990], Slovakia [1990], South Africa [1990]
