Show project ids and the number of documents in each project.
SELECT project_id ,  count(*) FROM Documents GROUP BY project_id
SELECT project_id ,  count(*) FROM Documents GROUP BY project_id
[{'Project_ID': 30, 'count(*)': 3}, {'Project_ID': 35, 'count(*)': 3}, {'Project_ID': 105, 'count(*)': 5}, {'Project_ID': 134, 'count(*)': 3}, {'Project_ID': 195, 'count(*)': 1}]