Zimbabwe’s new gold-backed currency started trading on Monday amid doubts that the country’s third such relaunch in a decade will have any more success in ending repeated, crippling bouts of high inflation.The Zimbabwe Gold (ZiG) was announced on Friday by the central bank with an initial rate of 13.56 to $1, replacing the Real Time Gross Settlement dollar (RTGS), which had lost about 80% of its value this year and had been trading at 28,720 to $1 before the change.Bank balances were transferred into the new currency over the weekend while their customers will have 21 days to do so, and…