An invoice for a shipment is shown below. The delivery fee is calculated as a percentage of the cost of the order. The grand total is the sum of the cost of the order and the delivery fee.
$$ \text{Invoice Details} $$ $$ \begin{array} {c|c} 20 & \text{Item \#3892} \\ 15 & \text{Item \#2215} \\ 5 & \text{Item \#3100} \\ \end{array} $$ $$ \begin{aligned} \text{Delivery Fee: }& \$25.28 \\ \text{Grand Total: }& \$193.78 \end{aligned} $$What percentage of the cost of the order was used to calculate the delivery fee?