Advertising Data is relatively tricky to find. Companies typically include their own advertising expenditures in the much broader category "Selling, General & Administrative Expenses" or SG&A on their financial statements. As a result, very few aggregators make an effort to calculate advertising expenditures or ratios for either companies or for industries. Fortunately, there are a few that do.
Here's a short video illustrating how to find the ratio in Mergent. Please be aware that not every company will offer the data, that said, it will work as a nice estimate for the companies that do have the data.
Here's a short video on how to pull out advertising data from SimplyMap. Pulling data from SimplyMap is somewhat tricky, so please don't hesitate to ask questions if any arise.