Occurence

[Gribouillis]

First look at this, and take the time to understand it with the python documentation

>>> L = [1, 5, 2, 1, 2, 3, 5, 1, 5]
>>> sorted(set(L))
[1, 2, 3, 5]

Now replace lines 10 - 12 with

    for item in sorted(set(L)):
        count = L.count(item)
        print(item + ":" + "\""+str(count)+"\"" )

You can also remove L2 from the code.