How to create a row level calculated field in Google Data Studio?

If my table looks like:

Date        Conversions Clicks
2020-02-10      2           20
2020-02-09      50          80

And I'd like to add a calculated field of Ratio (conversions/clicks), which should look like:

Date        Conversions Clicks      Ratio
2020-02-10      2           20      10%
2020-02-09      40          80      50%

But if I remove the Date dimension that it looks like:

Conversions Clicks      Ratio
    42          100     60%

When it should look like:

Conversions Clicks      Ratio
    42          100     42%

In other words, it sums up the original ratios instead of re-calculating them as a total.

What can be done to fix this situation?