see How to come to data for a WF-RepTool report in general?
Options to come yield data (see video What means yield and what means composition?) are:
* use the regular documentation on yields of fractions (e.g. paper/IT documentation, e.g. shift reports or daily/weekly reports or aggregated annual reports)
* if not available: if possible adapt the process and documentation procedure to get separate yield data for WEEE input categories
* if not possible: run a batch to determine data