Roll Die - frequency counter

import java.util.Random;

public class RollDie {

    public static void main(String args[]) {
        Random randomNumbers = new Random(); // random number generator

        int frequency[] = new int[6]; // maintains count of 1 to 6s rolled

        int face; // stores most recently rolled value

        // summarize results of a billion rolls of a die
        for (int roll = 1; roll <= 100000000; roll++) {
            face = 1 + randomNumbers.nextInt(6); // number from 1 to 6

            // determine roll value 1-6 and increment appropriate counter
            switch (face) {
                case 1:
                    ++frequency[0]; // increment the 1s counter
                    break;
                case 2:
                    ++frequency[1]; // increment the 2s counter
                    break;
                case 3:
                    ++frequency[2]; // increment the 3s counter
                    break;
                case 4:
                    ++frequency[3]; // increment the 4s counter
                    break;
                case 5:
                    ++frequency[4]; // increment the 5s counter
                    break;
                case 6:
                    ++frequency[5]; // increment the 6s counter
                    break; // optional at end of switch
            } // end switch
        } // end for

        System.out.println("Face\tFrequency\tPercentage"); // output headers

        for (int i = 0; i < 6; i++) {
            System.out.print(i);
            System.out.print("\t");
            System.out.print(frequency[i]);
            System.out.print("\t");
            System.out.print((frequency[i] / 1000000) * 100);
            System.out.println();
        }
    } // end main
} // end class RollDie