A report by PWC and The World
According to the report, the 15 largest gold producing countries accounted for around 75% of global output. In 2012, these countries generated a gross value added (GVA) approximately equal to the GDP of Ecuador or Azerbaijan and 30% of the estimated GDP of Shanghai.
Gross Value Added refers to the "economic contribution of those entities engaged in the gold value chain and reflects their contribution to the economies in which they operate - and employment," according to the report.
Here is a chart that shows the top 15 gold producers and the value of their GVA in $ billions as well and as a percent of their GDP.