text: Below is an context that describes a sql query, paired with an question that provides further information. Write an answer that appropriately completes the request.  # noqa: E501
  ### Context:
  CREATE TABLE table_171748_3 (period VARCHAR, _percentage_trains_arriving_within_5_mins_of_scheduled_time_moving_annual_average__maa_ VARCHAR)
  ### Question:
  When was the percentage of trains arriving within 5 minutes of scheduled time 89.6%?
  ### Answer:
  SELECT period FROM table_171748_3 WHERE _percentage_trains_arriving_within_5_mins_of_scheduled_time_moving_annual_average__maa_ = "89.6%"