15-22. Use the following data to calculate the appropriate percentages for a sales funnel efficiency analysis of a banner ad campaign. The average click-through rate for banner ads is 0.5 percent. There were 40,000 visits/impressions and 450 click-throughs, 260 browsed products on the website, 225 placed items in the shopping cart, 196 made a purchase, and 156 created accounts. Which areas would be of most concern to marketers? Why?