I need help returning the "instance" of a particular item

[NukedWhale]

Countif tells me that I have four instances of a particular item. I want a formula or method to tell me the ordered "instance" of each one. So let's say I have 3 columns.

Column 1 (Raw Data)

A

B

A

A

Column 2 (The amount of times each letter appears)

3

1

3

3

Column 3 (My desired column which will tell me the ordered instance of each letter)

1 (First time A appears)

1 (First time B appears)

2 (Second time A appears)

3 (Third time A appears)

How do I get my desired results for Column 3?