sql server - Add row number to this T-SQL query

Question

How can I add ROW numbers to this query result?

SELECT DISTINCT
  VehicleSpecs.SubmittedById,
  COUNT(VehicleSpecs.SubmittedById) AS NumCars,
  aspnet_Users.UserName
FROM
  VehicleSpecs
  INNER JOIN aspnet_Users ON VehicleSpecs.SubmittedById = aspnet_Users.UserId
WHERE
  (LEN(VehicleSpecs.SubmittedById) > 0)
GROUP BY
  VehicleSpecs.SubmittedById,
  aspnet_Users.UserName
ORDER BY
  NumCars DESC

Answer 1

Add: ROW_NUMBER() OVER (ORDER BY NumCars)

EDIT:

WITH    t1 AS 
( SELECT DISTINCT
            VehicleSpecs.SubmittedById ,
            COUNT(VehicleSpecs.SubmittedById) AS NumCars ,
            aspnet_Users.UserName
   FROM     VehicleSpecs
            INNER JOIN aspnet_Users ON VehicleSpecs.SubmittedById = aspnet_Users.UserId
   WHERE    ( LEN(VehicleSpecs.SubmittedById) > 0 )
   GROUP BY VehicleSpecs.SubmittedById ,
            aspnet_Users.UserName
)
SELECT  ROW_NUMBER() OVER ( ORDER BY NumCars ), *
FROM    t1
ORDER BY NumCars