Aggregating quantitative data in an options set attribute?

Hi there!

I am looking for your thoughts and guidance on calculating the foundation of a line chart.

Suppose I have a data type that contains one field with dates and another field with entries from an options set. This set’s options are text but there are also numbers as attributes.

Now, I am trying to set up an expression that groups this type by date and aggregates the options according to their quantitative attributes.

This does not seem to work: I cannot select the field that contains the options (alright - how would you average text?) that contains the quantative attribute (why not?).

Does this simply not work? Do calculative aggregations always need bare-bones numbers or date fields? What might be a good workaround?

Thank you for your help!