What was the main date of the round with 20 fixtures?
CREATE TABLE table_61173 (
    "Round" text,
    "Main date" text,
    "Number of fixtures" real,
    "Clubs" text,
    "New entries this round" text,
    "Prize money" text
)
SELECT "Main date" FROM table_61173 WHERE "Number of fixtures" = '20'
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 was the main date of the round with 20 fixtures? ### Input: CREATE TABLE table_61173 (
    "Round" text,
    "Main date" text,
    "Number of fixtures" real,
    "Clubs" text,
    "New entries this round" text,
    "Prize money" text
) ### Response: SELECT "Main date" FROM table_61173 WHERE "Number of fixtures" = '20'