Counting the numbers between an interval [E{X}-σ, Ε{X}+σ]

import java.util.ArrayList;
import java.util.Random;

public class Stats {

    // Variables
    static int average = 10;
    static int stdDeviation = 1;
    static int size = 1000000;

    // Constructor
    Stats(){
        average = 0;
        stdDeviation = 1;
    }

    // MAIN FUNCTION
    public static void main(String[] args) {

        Random random = new Random();
        ArrayList <Double> list = new ArrayList <Double> ();
        for(int i=0; i<size; i++) {
            double r = random.nextGaussian() * stdDeviation + average;
            list.add(r);
        }
        // Now, my list is completed with random numbers
        double sum = list.get(0);
        double max = list.get(0);
        double min = list.get(0);
        for(int i=1; i<list.size(); i++) {
            sum += list.get(i);
            if(list.get(i) > max) {
                max = list.get(i);
            }
            if(list.get(i) < min) {
                min = list.get(i);
            }
        }
        // Now, I will count how many numbers are in the range [9, 11] = [average - deviation, average + deviation]
        int sum2 = 0;
        for(int i=0; i<list.size(); i++) {
            if((list.get(i) >= average - stdDeviation) && (list.get(i) <= average + stdDeviation)) {
                sum2++;
            }
        }
        // Display the statistics of my survey
        System.out.println("I will generate " + size + " random numbers, that follow Gaussian ");
        System.out.println("distribution with average = " + average + " and stdDeviation = " + stdDeviation + ".");
        System.out.println();
        System.out.println("* Max number generated: " + max);
        System.out.println("* Min number generated: " + min);
        System.out.print("* There are " + sum2 + " numbers out of " + size + ", that are in the range [" + (average-stdDeviation));
        System.out.println(", " + (average+stdDeviation) + "].");
        double percentage = (double)sum2 / (double)size;
        System.out.println("This means that " + (100*percentage) + "% of the generated numbers exist in the interval: ");
        System.out.println("[E{X} - σ, E{x} + σ] = [average - stdDeviation, average + stdDeviation]");
        System.out.println();

    }   // END OF MAIN FUNCTION

}   // END OF CLASS