For Assemblies - What is the Location of Extraction?

My client has a chair which was manufactured within 500 miles of the project site. The chair is composed of foam (5%), plastic (2%), wood (13%) and steel (80%) by weight. The steel is sourced from a company in Toronto that makes steel furniture frames (within 500 miles of project site). The Toronto company purchases steel bars from a company in Ontario (not within 500 miles of project site). The Ontario company gets their steel from a quarry/recycling plant in Alberta (not within 500 miles of project site). It is my understanding that LEED only cares about the manufacturing location and the location that the manufactured materials have come from (the previous location.) LEED does not track more than two levels of where materials come from. There is no clear guidance I can find on which of the three locations listed above (Toronto, Ontario or Alberta) should be considered to be the extraction location. Based on your experience, is this chair 80% extracted within 500 miles of the project site or not?