Most of those statistics are self- reported by governments looking for ways to hide their problems. The premature birth statistics, for example, never mention how each country defines still-born. Now you might think the definition is obvious but then you've never thought about how hard governments work to hide their failings. Anyway, greatest is not a matter of statistics, it's a matter of feelings, and when the population inflow in a hundred times the population outflow you are doing something right. As for the slavery question, please first list the countries that never had slavery.