Table schema:
CREATE TABLE table_name_71 (population INTEGER, area_km_2 VARCHAR, official_name VARCHAR)

Question: What is the average population vlue for an area smaller than 26.69 square km and has an official name of Rogersville?
SQL: SELECT AVG(population) FROM table_name_71 WHERE area_km_2 < 26.69 AND official_name = "rogersville"