nrur: Resource Usage Rate
Variable
Nonrenewable resource sector
Resource Usage Rate [Resource units/year]
nrur = pop * pcrum * nruf

nrur in the updating graph: ( how to read )
In nodes
nruf : resource use factor
pcrum : per capita resource use multiplier
pop : population
Out nodes
nr : Nonrenewable Resources
resint : resource use intensity
rtcm : resource technology change rate multiplier