what is all the broadcast date when viewers were 8.4 millions
CREATE TABLE table_24168 (
    "Episode" text,
    "Broadcast date" text,
    "Run time" text,
    "Viewers (in millions)" text,
    "Archive" text
)
SELECT COUNT("Broadcast date") FROM table_24168 WHERE "Viewers (in millions)" = '8.4'
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 is all the broadcast date when viewers were 8.4 millions ### Input: CREATE TABLE table_24168 (
    "Episode" text,
    "Broadcast date" text,
    "Run time" text,
    "Viewers (in millions)" text,
    "Archive" text
) ### Response: SELECT COUNT("Broadcast date") FROM table_24168 WHERE "Viewers (in millions)" = '8.4'