CREATE TABLE Document_Types (document_type_code VARCHAR2, document_description VARCHAR2)
CREATE TABLE Research_Staff (staff_id NUMBER, employer_organisation_id NUMBER, staff_details VARCHAR2)
CREATE TABLE Staff_Roles (role_code VARCHAR2, role_description VARCHAR2)
CREATE TABLE Project_Outcomes (project_id NUMBER, outcome_code VARCHAR2, outcome_details VARCHAR2)
CREATE TABLE Grants (grant_id NUMBER, organisation_id NUMBER, grant_amount NUMBER, grant_start_date DATETIME, grant_end_date DATETIME, other_details VARCHAR2)
CREATE TABLE Project_Staff (staff_id DOUBLE PRECISION, project_id NUMBER, role_code VARCHAR2, date_from DATETIME, date_to DATETIME, other_details VARCHAR2)
CREATE TABLE Organisations (organisation_id NUMBER, organisation_type VARCHAR2, organisation_details VARCHAR2)
CREATE TABLE Projects (project_id NUMBER, organisation_id NUMBER, project_details VARCHAR2)
CREATE TABLE Documents (document_id NUMBER, document_type_code VARCHAR2, grant_id NUMBER, sent_date DATETIME, response_received_date DATETIME, other_details VARCHAR2)
CREATE TABLE Tasks (task_id NUMBER, project_id NUMBER, task_details VARCHAR2, "eg Agree Objectives" VARCHAR2)
CREATE TABLE Organisation_Types (organisation_type VARCHAR2, organisation_type_description VARCHAR2)
CREATE TABLE Research_Outcomes (outcome_code VARCHAR2, outcome_description VARCHAR2)

When do all the researcher role staff stop working? Bin the time into YEAR interval and count them with a line chart, and could you show by the X in desc?
SELECT date_to, COUNT(date_to) FROM Project_Staff ORDER BY date_to DESC
SELECT "date_to", COUNT("date_to") FROM "Project_Staff" ORDER BY "date_to" DESC