@Ariella, you raised a great point. I was of the view that books on careers were focused on inwards discovery and overlooked the category because market discoveries would become obsolete due to the long process that starts at the writer and ends with a publication.
And as you rightly said, local and national averages are also a vital consideration. The economics of information sharing can also create unexpected results. For instance, if a local region has 500 open positions for accountants, a publisher manages to disseminate the news, resulting in 5,000 individuals signing up for accounting classes, it only creates surplus skills.