Hello @mlauber71!
Thanks for your response. But I do not really understand what you exactly mean (I am sorry 
) . To get rid of the “%” I converted these numbers in my excel table from percetage to number (5,351% --> 0,05351). I also multiplied these numbers than with the factor of 100. Unfortunately, the columns UW and MW are still marked as ‘S’ columns and I cannot select them in the GLM regression node.