It's simple, you are a rancher in the oklaomaha, you have to off load your herd in 2 months, never go to town... you get it by the vet who came to visit, you have a r0 hyper low...
on the other hand you are dentists, you have 10's of patients per day... and love tango dancing two time per week...
there it goes....
that's why I am thinking that this value is quite irrelevant, it really depends of the individual and this avg value is just totally unworkeable in reality...
that's at least my understanding of this parameters... and I ain't no expert, my logic could be flawed, but I don't see how :D.