Consider a warehouse with 5 SKU's. The unit selling prices for these items are $91, $5, $444, $500, and $598 respectively. The annual sales volumes for these 5 items are 987 units, 1,000 units, 2,000 units, 20 units, and 451 units. According to our discussion on inventory profiling, what percentage of the annual sales is the result from the top 20 % of the SKU's?