For selected Event Label results are:
How to present in custom report value of CTR [%] = (Total Events for Click) / (Total Events for Hit)?
1
1
Unfortunately there is no way to perform calculations of this type within Google Analytics or Google Data Studio. You can divide one metric by another (such as Unique Events / Total Events), but not one dimension's metric value by another dimension's metric value.
If you need this on an ongoing basis, so it's worth some extra work to set up a report, you can do it in Google Sheets with the Google Analytics Add-On. The add-on documentation will get you started. Your actual report would be in a different tab of the spreadsheet, where you can copy over data directly from the GA reports and also do whatever arithmetic is useful to you.
