CREATE TABLE roller_coaster (Roller_Coaster_ID NUMBER, Name CLOB, Park CLOB, Country_ID NUMBER, Length FLOAT, Height FLOAT, Speed CLOB, Opened CLOB, Status CLOB)
CREATE TABLE country (Country_ID NUMBER, Name CLOB, Population NUMBER, Area NUMBER, Languages CLOB)

Show the names of countries and the average speed of roller coasters from each country. Plot them as bar chart.
SELECT T1.Name, AVG(T2.Speed) FROM country AS T1 JOIN roller_coaster AS T2 ON T1.Country_ID = T2.Country_ID GROUP BY T1.Name
SELECT "T1"."Name", AVG("T2"."Speed") FROM "country" "T1" JOIN "roller_coaster" "T2" ON "T1"."Country_ID" = "T2"."Country_ID" GROUP BY "T1"."Name"