The graphs are showing you the trends in the stock. There's a solid line with two grey lines, one on either side. So those represent what we call the 95% confidence intervals around the estimates. The closer those lines are to the value, the more certain we are that we have things right. I think you can see in the recent period that the confidence bands are fairly narrow, so we're quite confident that we have good information on the status of the resource today.
On September 21st, 2016. See this statement in context.