adding a column representing the sequence of duplicates in a specific column

[iestat]

Hi Guys!

I have a variable (column) named ID and there are some duplicates therein. I want to add a new column showing the sequence of duplicates in ID. For example if we have three values of 10 in a line for ID consecutively, there should be 1, 2, and 3 for the new SEQ column respectively. Attached you can easily see what I mean to do. How could it be done?

Thanks!