Your own link says this at the bottom of the introduction:

> In recent years, the discount rate has been approximately a percentage point above the federal funds rate (see Lombard credit). Because of this, it is a relatively unimportant factor in the control of the money supply and is only taken advantage of at large volume during emergencies.

And in recent years the economy in general have been on life support. No lending, no need for the discount window to line up the numbers.