Database: country_language
Question: What are the names of the official languages, sorted descending by the average overall scores across the countries that correspond to each?
SQL:
SELECT T3.name FROM countries AS T1 JOIN official_languages AS T2 ON T1.id  =  T2.country_id JOIN languages AS T3 ON T2.language_id  =  T3.id GROUP BY T3.id ORDER BY avg(T1.overall_score) DESC