@andrehl, which version of Splunk are you on? Also what is the visualization to depict above output? Is it table or something else?
If you are on Splunk 6.5 or higher you can use Table format option to add Unit as % rather than adding % in the eval SPL command. This way your data remains numeric and still displays % in the column.
Refer to Splunk Documentation: https://docs.splunk.com/Documentation/Splunk/latest/Viz/TableFormatsXML#Number_format_rules
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