cncventure,
By dividing reported EBIT by current Ev (ie market cap less cash plus debt).
By comparison, here are a few other ASX-listed goldies and what I calculate their EBIT/Ev to be:
Beadell = 11% (6m numbers)
Regis = 10% (FY)
Evolution = 10% (FY)
Northern Star = 6% (FY)
Newcrest = 3% (FY)
Kingsgate = -1% (FY)
Silverlake = -15% (FY)
St Barbara = -22% (FY)
Perseus = -30% (FY)