SELECT avg(revenue) ,  max(revenue) ,  sum(revenue) FROM manufacturers
What are the average, maximum and total revenues of all companies?
[Schema (values) (types)]: | manufactory_1 |  Manufacturers : code (text) , name (number) , headquarter (text) , founder (text) , revenue (text) | Products : code (text) , name (number) , price (text) , manufacturer (text);