On the sample dataset db_employees:

1. Compute the number of employees hired in each year
2. Find the manager who is currently spending more time managing the same department
3. Find the manager who has spent the most time managing the same department
4. Find the department that has the most employees
5. Find the department that has had (now, or in the past) the most employees in any given moment
6. Find the department that has had (now, or in the past) the most employees (sum all current and past employees).
7. Compute how the current salaries are distributed among all departments
8. Find the employee that has earned the most, throughout its career