This is another subject area where articles from trade publications are invaluable. Both ABI-INFORM and Business Source Premier have articles in publications about advertising such as Advertising Age that will include information about businesses in your industry.
Don't forget that IBISWorld profiles include marketing costs as a percentage of revenue under the "Competitive Landscape" tab.
Also, data on advertising is available in most First Research Industry Reports (available in ABI-Inform).
Advertising Age puts out an annual report of ad spending by channel of the top 100 advertisers. The last two annual issues are in the Periodicals room, in the hanging files, in the folder marked with a blue dot. This information is also available in the database Statista.
If you need to figure out how much a company spends on television advertising and you can't find that information in an article, you can estimate the spending by using this report. First you will need the total amount the company spends on advertising. If you can't find that you can use an industry average. Then you will find a company in your industry that appears on the list of the top 100 advertisers. If you can't find one in the exact same industry, use one that behaves the same way in the marketplace, for instance is also a company that markets a non-durable consumer good. Then divide the amount your chosen company spends in each channel by the company's total ad budget. This will create percentages that you can then apply to the advertising budget of your company.
Your company spends $100,000 in advertising.
Big 100 company spends $5,000,000. They spend $2,000,000 of that total on television advertising.
$2M /$5M = .40 or 40%
$100,000 * .40 = $40,000
You can estimate that your company spends $40,000 a year on television advertising. If you use this method, document where you got your original numbers and show how you created your estimate!
The first resource to check is a reference work, Ad Ratios & Budgets that comes with a CD of the files.
Call number, book: REF HF5801 .A344 Call number, CD is REF HF5801 .A344 2014.
If you get the CD from the circulation desk in the library, you'll be able to search for your industry, and then copy and save the data. The document below shows the information available in the files.
In addition to these sources, The Almanac of Business and Industrial Financial Ratios (REF HF5681 .R25 T68) also includes advertising as a ratio of sales.