How many of the workers who started working in 2009 are from the Production Department?
StartDate BETWEEN '2009-01-01' AND '2009-12-31';
SELECT COUNT(T2.BusinessEntityID) FROM Department AS T1 INNER JOIN EmployeeDepartmentHistory AS T2 ON T1.DepartmentID = T2.DepartmentID WHERE T2.StartDate >= '2009-01-01' AND T2.StartDate < '2010-01-01' AND T1.Name = 'Production'