Even though you do refer to the "staff", and a member of the staff, when dealing with the hotel industry, in term of yearly financial reports, where standard terms are not linked to a given industry, the concept of "staff" actually refers to upper echelon employees (such as those refered to as "white collars" or those "on salary", to the exclusion of those "on wages"), and, therefore, the term "effectifs", in this particular case, should be translated by "workforce". Thus my proposition.
Hope this help.