filtering a skill matrix

Thanks for your help.. I manged to draw a quite nice and comprehensive spider chart.

I have countries as the "pillars" of the web and have the average and max skill values as "y-axxis" values.

I now want to add a slicer to make this less complex to view. But l ran into the following problems

1. I want to select "Skill 1" in a list and the average and max value should be displayed in the chart. So 1 entry in the slicer controlling 2 dataset on the chart -> is this possible?

2. I have no data field to use as a "skill list" to select from. How can I create such a list for a slicer.

I tried to add a column "Skills" with all the skills as rows. But this is not linked to my data. How to manage this?