Is Article 14(2) of Regulation (EC) No 987/2009 of the European Parliament and of the Council of 16 September 2009 laying down the procedure for implementing Regulation (EC) No 883/2004 on the coordination of social security systems to be interpreted as meaning that, in order for it to be possible to assume that an undertaking engaged in providing temporary personnel normally carries out its activities in the Member State in which it is established, it has to perform a substantial part of the employee assignment activity for hirers established in the same Member State?