Show the names of countries and the average speed of roller coasters from each country.
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 AS T1 JOIN roller_coaster AS T2 ON T1.Country_ID  =  T2.Country_ID GROUP BY T1.Name
[{'Name': 'Austria', 'avg(T2.Speed)': 58.666666666666664}, {'Name': 'Finland', 'avg(T2.Speed)': 47.45}, {'Name': 'Sweden', 'avg(T2.Speed)': 67.0}]