CREATE TABLE phone (chip_model VARCHAR(255), Company_name VARCHAR(255)); CREATE TABLE chip_model (ROM_MiB INTEGER, Model_name VARCHAR(255))
What is the average ROM size of phones produced by the company named "Nokia Corporation"?
    
SQL: SELECT AVG(T1.ROM_MiB) FROM chip_model AS T1 JOIN phone AS T2 ON T1.Model_name = T2.chip_model WHERE T2.Company_name = "Nokia Corporation"