const count = 1000
const scores = [...(new Array(count))]
    .map((_, index) => ({
      x: index + 1,
      y: (Math.random() * 100) * (1 - Math.random())
    }))

const sum = scores
    .map(score => score.y)
    .reduce((acc, curr) => acc + curr );
const mean = sum/count;
const stddev = scores
    .map(score => score.y)
    .reduce((acc, curr) => ((mean - curr) ** 2))/mean;

const zScores = scores.map(({x, y}) => ({
    x,
    y,
    z: ((y - mean)/mean)
}))