let total = 20;

​

function setup() {

  createCanvas(640, 240);

  for( let i = 0; i<total; i++){

    randomCounts[i] = 0;

  }

}

​

function draw() {

  background(127);

  let index = floor(random(total));

  randomCounts[index]++;

  stroke(0);

  strokeWeight(2);

  fill(255);

  let w = width/randomCounts.length;

  for (let x=0; x < randomCounts.length; x++) {

    rect(x*w, height-randomCounts[x], w-1, randomCounts[x]);

  }

}