My first year doing Advent of Code was 2015, back when I was a student and had all the time in the world. Good times. These days I am lucky if I make time to do even one problem.
My best year was 2018, where I got 21 stars. This coincides with my summer internship at First Derivatives, where I completed their month-long KDB training program in a week (on account of my experience with array-oriented programming) and thereafter spent some time doing Advent of Code and Project Euler problems. That was wonderful. My participation in years 2015 (8*), 2017 (17*) and 2019 (2*) aren't here, and I'm sadly I don't know where the code is. I probably used J and Q/K for most of the early years, since for a long time my favourite kind of programming was array-oriented programming.