text: SELECT YEAR (d.from_date) as calendar_year, gender, COUNT (e.emp_no) as num_of_employees
  FROM t_employees e JOIN t_dept_emp d
  on d.emp_no = e.emp_no
  GROUP BY calendar_year, e.gender
  HAVING calendar_year >= 1990;
  
  -- Should return 26 rows of data
  