Grouping the same values by a number sequence for a column

I am trying to group the same values in columns together and i was thinking about having a number count. What's the function that might be able to display this (display whats in Column B in the example below)?

Values
5000 1
5000 1
6000 2
7000 3
7000 3
8000 4
8000 4
8000 4
9000 8
10000 9
10000 9