This is a third-party script/app and is not created by the WaniKani team. By using this, you understand that it can stop working at any time or be discontinued indefinitely.
When you are doing a review, you might notice, that the percentage shown during the review isn’t the same as the one shown after the review.
This script “corrects” that by changing the one shown during review to the one shown after it.
Installation
You can download the userscript from here: WK Percentage Unifier
General userscript installation guide: Visual Guide on How To Install A Userscript
How it works
The percentage shown after a review works on a per item basis. If you have 3 items you missed something in and 5 items that you reviewed perfectly, it will show 5 / (5 + 3) ≅ 63%
The percentage shown during reviews on the other hand works on a per review basis. If you have 2 items, where you missed both the reading and meaning once each, 1 item where you only missed the meaning and 5 items you answered perfectly, that will be 16 correct reviews (8 items each with meaning and reading) and 5 incorrect reviews (2 * 2 + 1), that means the percentage will be 16 / 21 ≅ 76%.
The script just takes the first option and makes it the case during reviews as well.