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

Show the names of countries and the average speed of roller coasters from each country with a bar chart, and show by the bars in desc please.
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 ORDER BY T1.Name DESC
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" ORDER BY "T1"."Name" DESC NULLS LAST