Zimbabwean President Robert Mugabe on Sunday opened a summit of southern African leaders by calling for countries to drive growth by exporting more finished goods instead of raw materials.\nThe 90-year-old leader took over as chairman of the Southern African Development Community from Malawi's Peter Mutharika after almost a decade of being excluded from positions of power in the 15-member bloc.\nHe is also in line to lead the 54-nation African Union from next year.\nHe told the opening of the two-day summit that Southern Africa must \wean itself from exporting raw materials and create value chains that will lead to the exportation of finished products.\\nMugabe has ruled Zimbabwe since independence in 1980 but a series of economic crises