Give a number value based on where the item falls in a list?

[Tiger1]

I need an expression to help me place a value of the items in a list.  

The List:

This list is in order of least to greatest (Based on location distance).  I need to put a value (starting with the number 1 ) going up for each item in the list.

My list:

Column I need to add the values of each of these items.  Again the value will be a number according to where they are in this list.

For example,

From the list above the first number (40123404) would get the value "1",  The number (40123431) would get the value "2", and so on.....