When was the percentage of trains arriving within 5 minutes of scheduled time 89.6%?
CREATE TABLE table_1635 (
    "Period" text,
    "% trains arriving within 5 mins of scheduled time (over three months)" text,
    "Change over same quarter the previous year" text,
    "% trains arriving within 5 mins of scheduled time Moving Annual Average (MAA)" text,
    "Change over previous year as a whole" text
)
SELECT "Period" FROM table_1635 WHERE "% trains arriving within 5 mins of scheduled time Moving Annual Average (MAA)" = '89.6%'
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: When was the percentage of trains arriving within 5 minutes of scheduled time 89.6%? ### Input: CREATE TABLE table_1635 (
    "Period" text,
    "% trains arriving within 5 mins of scheduled time (over three months)" text,
    "Change over same quarter the previous year" text,
    "% trains arriving within 5 mins of scheduled time Moving Annual Average (MAA)" text,
    "Change over previous year as a whole" text
) ### Response: SELECT "Period" FROM table_1635 WHERE "% trains arriving within 5 mins of scheduled time Moving Annual Average (MAA)" = '89.6%'