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_12983929_1 (construction_start VARCHAR, commercial_operation VARCHAR)
### Question:
When was the start of the construction of the unit that's been in commercial operation since 04.03.1987?
### Answer:
SELECT construction_start FROM table_12983929_1 WHERE commercial_operation = "04.03.1987"