Transact SQL :: Order Of XML Nodes In Xpath Query

I have an XML field with some data that looks about like this:

<steps>
<step userName="abc"></step>
<step userName="abc"></step>
<step userName="saf2"></step>
<step userName="abc"></step>
</steps>

I have a query something like this:

SELECT XmlField.value('(//step/@userName)[1]', 'VARCHAR(100)') AS userName
FROM theTable

I would like to have some kind of indicator in my TSQL results of the number of each <step> node.  For instance, saf2 would be a 3.  I think this is similar to a ROW_NUMBER() kind of function in normal table data.

Is there a good way to get a 1, 2, 3, and 4 value for this sample data?