Dice frequency calculations

tabletop = [19, 16, 2, 19, 15, 4, 9, 5, 2, 13, 7, 5, 18, 5, 1, 5, 3, 5, 20, 3]
dicetower = [7, 6, 2, 15, 16, 1, 8, 17, 1, 6, 4, 8, 6, 4, 8, 11, 3, 15, 6, 6, 2, 2, 8, 12, 12, 17, 2, 1, 1, 16, 1, 3, 15, 12, 1, 11, 11, 4, 1, 4, 8, 1, 5, 13, 15, 7, 17, 14, 9, 4, 5, 20, 13, 20, 1, 2, 5, 4, 3, 8, 2, 10, 6, 2, 4, 5, 14, 11, 13, 15, 19, 2, 8, 2, 1, 1, 4]


def freq(rolls):
    results = {}
    for i in range(1, 21):
        results[i] = 0
    for roll in rolls:
        results[roll] += 1
    return results

def analyse(rolls):
    freqs = freq(rolls)
    for roll in freqs:
        count = freqs[roll]
        print str(roll) + ": " + ("." * count) + " (" + str(count) + ")"

    print "Results by quartile:"
    print "1-5:   " + str(sum([freqs[c] for c in range(1, 6)]))
    print "6-10:  " + str(sum([freqs[c] for c in range(6, 11)]))
    print "11-15: " + str(sum([freqs[c] for c in range(11, 16)]))
    print "16-20: " + str(sum([freqs[c] for c in range(16, 21)]))

# Run this and call either analyse(dicetower) or analyse(tabletop)