Look first for what's built into your Business Plan Pro, in the ratios table, for no additional charge. It includes more than 9,000 reports with standard ratios for different types of businesses, at different sizes. Look into the ratios table for more information on that, and of course your documentation as well.
Also, check out your industry organization for specific industry numbers. They should have them, but if not, ask them to refer you to some of their volunteer leaders who will likely share some of their ratios.
Congratulations for asking such an appropriate question for business planning. You might be surprised at the number of people who don't even know that they should seek statistical information, let alone how helpful they can be.