Counting Intervals

mylist = [4,4,1,18,2,15,6,14,2,16,2,17,12,3,12,4,15,5,17,4,4,6]
count, I = 0, 0
for j in set(mylist):
    for i in mylist:
        if i == j:
            if I == 0:
                I=1
                count+=1
        else:
            I=0
    print "Index: %s. Count: %s" % (j, count)
    count, I = 0, 0