I like the idea of providing proof (works cited) to back up an opinion with facts as you have done. It's what you learn in college when you take breaks from binge drinking.
To be fair, however, much of the information you shared is some 14-17 years old. Meaning that 14-17 year old music fans are completely left out of your hypothesis.
I dont think that young people right now are into jazz...
The tendence is to a falling number of young jazz listeners...
With all the niche listening phenomenon , the increasing of the new medias Jazz cannot be an increasing favored genre ... It is evident...Jazz is now an old musical genre competing with new one...
This statistics only illustrated a tendency which cannot be decreasing anyway after the generalization of the internet use and portable phone from which many niche genre music appeared. There is no reason for this statistics to had changed because an increase of jazz which is a more intellectual music genre is less probable and ask for an education to it...
Another phenomena is masked here by this statistics concerning jazz falling numbers of young listeners, is the influence of jazz and easy diffusion now because of the internet all around the globe in all culture... jazz listeners has increased in the same time as young listeners of jazz in America had deceased...
Jazz has his roots in black America but it is no more an American event it is globalised and there is many jazz musicians of first order in all countries now...With internet since 25 years Jazz has be listened to freely everywhere..