Great question, I must say. The learned Societies in their libraries are great resources. Journal articles are also of great resources as well as credible industrial resources.

Thank you Ojo Ademola . I've been looking through my normal academic and library sources, but am having difficulty finding spend by Industry segment.

Many thanks, Joseph Kirby. I understood. It could be easier to search with specific industry keywords. For example, with Aviation, Education, Manufacturing, and more, searching or accessing government sites on such industries could be great sources! I'm just thinking!!!

My hope is that someone has examined this topic and I'm looking for such as study.

Maybe try Data and reports | U.S. Department of Commerce