dr: Death Rate
Variable
Global
Death Rate []
dr = p * clip ( drn , drn1 , swt3 ,time)* drmm * drpm * drfm * drcm

dr in the updating graph: ( how to read )
In nodes
drcm : death-rate-from-crowding multiplier
drfm : death-rate-from-food multiplier
drmm : death-rate-from-material multiplier
drn : death rate normal (fraction/year)
drn1 : death rate normal no. 1 (fraction/year)
drpm : death-rate-from-pollution multiplier
swt3 : switch time no. 3 for drn (years)
p : population
Out nodes
p : population