I think advertising can take many forms, and dollars spent is not always the best measure.
One year I spent $1500 on advertising in one newspaper, and got 2 phonecalls.
This year I've spent $0 on advertising, except for yellow pages. Though I have spent $30-40 on paper and ink. I'm not sure if you are all in the identical business that I am, but I think our business is different than those that those marketing studies are done for.
My customers may only look to hire a landscaping firm 2 or 3 times in a lifetime. So I have to ask myself if I'm willing to spend money year after year so that person remembers me on those 2 or 3 occasions.
I would rather hit them right at the moment they are actively searching for a firm.