What year had a date of TBA where the Oakland raiders were the home team?
CREATE TABLE table_40950 (
    "Year" real,
    "Date" text,
    "Television" text,
    "Designated Visitors" text,
    "Designated Home" text,
    "Stadium" text,
    "City" text
)
SELECT AVG("Year") FROM table_40950 WHERE "Date" = 'tba' AND "Designated Home" = 'oakland raiders'
Below are sql tables schemas paired with instruction that describes a task. Using valid SQLite, write a response that appropriately completes the request for the provided tables. ### Instruction: What year had a date of TBA where the Oakland raiders were the home team? ### Input: CREATE TABLE table_40950 (
    "Year" real,
    "Date" text,
    "Television" text,
    "Designated Visitors" text,
    "Designated Home" text,
    "Stadium" text,
    "City" text
) ### Response: SELECT AVG("Year") FROM table_40950 WHERE "Date" = 'tba' AND "Designated Home" = 'oakland raiders'