@Drugo, considering production for Mar'17 qtr through to Jun'20 qtr (i.e. 14 production quarters) it looks like they've produced 228,492oz which, according to the maths, suggests a historic quarterly average of 16,321oz....so I tend to agree with you....WMX should be capable of producing at least 15koz / qtr going forward. Based on the maths however, I'd be inclined to label 15koz / qtr as 'below average production' rather than 'good production'.
