The Japanese HS champs are this weekend and Brett Larner breaks it down for you here:
http://japanrunningnews.blogspot.com/2014/12/toyokawa-girls-looking-to-repeat-sera.html
Take a look at the boys PB chart here:
and the girls chart here:
Even if you take out the Kenyan from the top boys team, the 5 man avg would be under 14:20. What could a top US team average?