(Telecompaper) The amount of data traffic over mobile networks reached around 2,000 petabytes in the fourth quarter of 2013, an increase of 70 percent year-on-year and 15 percent more than in Q3 2013, according to Ericsson's latest Mobility Report on market statistics. Based on its own monitoring of a representative sample of mobile networks worldwide, Ericsson's report shows voice traffic growing little, despite a steady increase in mobile subscribers. Ericsson estimates there were 6.7 billion mobile subscriptions worldwide at the end of 2013, an increase of 109 million or 1.5 percent compared to the end of Q3 2013. Year-on-year, the global base grew by 6 percent, taking mobile penetration to 92 percent of the world's population. The actual number of mobile users is smaller, at an estimated 4.5 billion, due to many people having more than one mobile Sim. China and India each accounted for around 20 percent of subscriber additions in Q4, with the rest of Asia representing another 20 percent. The US also remained in the top five growth markets, with around 5 million subscribers added. Penetration is still at less than 100 percent in China (90%), Africa (72%) and India (59%). Mobile broadband subscribers grew even faster in Q4, increasing by around 40 percent year-on-year to 2.1 billion at year-end. LTE subscribers passed the milestone of 200 million by the end of 2013. Despite over 1 billion smartphones sold last year, Ericsson estimates that only 30 percent of mobile subscribers have the data devices, leaving considerable room for further uptake.