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 Documents (project_id VARCHAR, document_type_code VARCHAR)
### Question:
How many documents are with document type code BK for each product id?
### Answer:
SELECT COUNT(*), project_id FROM Documents WHERE document_type_code = "BK" GROUP BY project_id