How can I find out how much various US industries spend on advertising or other operating expenses?
The US Census Bureau provides data on business expenses for various kinds of businesses.
Choose the sector, then look for something that mentions "Detailed Operating Expenses" (the placement is not consistent for each sector, so look carefully at the available options). You'll find the amount spent on various kinds of operating expenses, including "Purchased advertising and promotional services," by each kind of business. If you need help, please contact the business librarian.