CREATE TABLE mission (Mission_ID NUMBER, Ship_ID NUMBER, Code CLOB, Launched_Year NUMBER, Location CLOB, Speed_knots NUMBER, Fate CLOB)
CREATE TABLE ship (Ship_ID NUMBER, Name CLOB, Type CLOB, Nationality CLOB, Tonnage NUMBER)

Give me a bar chart for mean tonnage of each type, display from high to low by the y-axis.
SELECT Type, AVG(Tonnage) FROM ship GROUP BY Type ORDER BY AVG(Tonnage) DESC
SELECT "Type", AVG("Tonnage") FROM "ship" GROUP BY "Type" ORDER BY AVG("Tonnage") DESC