The demand for disposable teaspoons in a cafeteria is $1000$ per week. Holding them in inventory costs $10\%$ per year $(52$ weeks per year$)$ over the unit value which is $$5.$ Currently the purchasing manager orders $4000$ units every $4$ weeks. If the supplier offers a discount of $$0\mathrm{.}20$ per teaspoon.

How many teaspoons would he advance an order to take advantage of the discount?