Table schema:
CREATE TABLE table_2637317_1 (change_in_population_since_1993 VARCHAR, _percentage_of_countrys_population VARCHAR)

Question: What is the change in population since 1993 in the region where the % of country's population was 4.2? 
SQL: SELECT COUNT(change_in_population_since_1993) FROM table_2637317_1 WHERE _percentage_of_countrys_population = "4.2"