Cape Town - Sub-Saharan Africa is set to remain the world's fastest growing mobile market in the coming years, an industry report said on Monday.According to the GSM Association, the region's number of unique subscribers stood at 253 million in June this year and is set to hit 346 million by 2017."Despite the astonishing progress of the mobile industry in Sub-Saharan Africa (SSA) in recent years, the biggest impact of mobile in Africa is yet to come," the report said."Roughly two thirds of the population are still without a mobile subscription, leaving much room for growth."The region's number of mobile users have grown by 18% annually over the past five years but penetration is the lowest in the world at close to 31%."This highlights the long-term growth potential of the region," said the GSMA.The continent's economic powerhouse South Africa's has 66% penetration, while the continent's biggest population Nigeria has reached 30%. The global average is nearly one in two users, and four out of five in the European Union.But while growth rates are slowing elsewhere, in sub-Saharan Africa this is set to remain at almost twice the global average.In sub-Saharan Africa, 95% of users are on prepaid plans."Incremental subscriber growth will come almost entirely from rural and lower income populations, reinforcing the need to further improve the affordability of mobile services and to extend network coverage," said the GSMA.Lowering taxes on mobile usage and phones was also highlighted in the report "Mobile Economy: Sub-Saharan Africa 2013".The sector's contribution to GDP is the highest in the world and is set to rise to over eight percent by 2020, said the report.