2017/699 establishing a common methodology for the calculation of the weight of electrical and electronic equipment (EEE) placed on the market of each Member State and a common methodology for the calculation of the quantity of waste electrical and electronic equipment (WEEE) generated by weight in each Member State (link)
In order to ensure uniform conditions for the calculation of the minimum annual collection rate of WEEE by the Member States in accordance with Directive 2012/19/EU, this regulation establishes a common methodology to be used by Member States where they calculate that collection rate based on the weight of electrical and electronic equipment (EEE) placed on their respective markets, as well as a common methodology for the calculation of the total quantity of WEEE generated by weight in each Member State, to be applied when that option becomes available to Member States in accordance with Directive 2012/19/EU.
Source: EC