Generally speaking, you'll want to present both. "From 6th to 7th grade, I went from 200 cm to 205 cm in height, a 2.5% increase." Otherwise, as you say, people will ask for N= or for %, or even starting asking for median IQR and statistical tests of difference. I do tire of oversimplistic analyses in popular media which present whichever one of the above measures is most in line with their narrative.