From 1960 to 1965, which country has the lowest value of indicator belongs to Health: Population: Structure?
From 1960 to 1965 refers to Year between '1960' and '1965'; the lowest value implies MIN(Value); country refers to CountryName;
SELECT CountryName FROM Indicators WHERE Value = ( SELECT MIN(T1.Value) FROM Indicators AS T1 INNER JOIN Series AS T2 ON T1.IndicatorName = T2.IndicatorName WHERE T1.Year >= 1960 AND T1.Year < 1966 AND T2.Topic = 'Health: Population: Structure' )