SQL SERVER STUFF FUNCTION VALUE INCREMENT COUNTER

I want to Add Counter in this query any idea ?

SELECT 
STUFF((
    SELECT ' , vol' + counter +' : ' + t2.ViaLocValue  
    FROM Book_ViaLocat t2
    WHERE t2.BookId = t1.BookId
    FOR XML PATH (''))
  ,1,2,'') AS Names
FROM Book_ViaLocat t1
WHERE t1.BookId = '167698'
GROUP BY t1.BookId;

result like this vol 1 : java2 , vol 2 : java3, vol 3 : java4