How to layout elements with set percentages

Hey there, I'm extremely new to the unity platform, so I do apologize if I am not using the correct terminology or if I am asking for something that's quite obvious. I am trying to make a VerticalLayoutGroup where the 3 elements within it have variable sizes based on the screen's size. Basically I'd like to set the sizes based on percentages (see image for clarification). Any help is more than appreciated, thanks in advance! :) ![alt text][1] [1]: /storage/temp/197861-screenshot-1.png