There seems to have been a shift in the makeup of the top national radio advertisers, according to Media Monitors. Insurance company Progressive has held fast to the top position, which it rose to a week ago. With 56,181 spots run around the country last week, it has continued the interruption to the familiar two-horse race between The Home Depot (41,170) and GEICO (37,628), which are now third and fourth on the list respectively. Vicks also continues to be at or near the top, this time taking second position with 50,694 ads. Completing the top five is McDonald’s with 36,004 spots. Walgreens has entered the upper reaches, landing at number eight (32,035).