Among the employees in the Manufacturing group in 2007, how many of them are store contacts?
store contact refers to PersonType = 'SC'; year(EndDate)>2007 and year(StartDate)<2007;
SELECT COUNT(T1.BusinessEntityID) FROM EmployeeDepartmentHistory AS T1 INNER JOIN Department AS T2 ON T1.DepartmentID = T2.DepartmentID INNER JOIN Person AS T3 ON T1.BusinessEntityID WHERE T3.PersonType = 'SC' AND T2.GroupName = 'Manufacturing' AND STRFTIME('%Y', T1.EndDate) >= '2007' AND STRFTIME('%Y', T1.StartDate) <= '2007'