Photo uploading and sharing is growing at an incredible pace, according to data shared by KPCB’s Mary Meeker in the Internet Trends report she presented on stage at D11. Well over 500 million photos are shared per day on average so far in 2013, the report estimates, which is on pace to become a 2x increase by the end of 2013, compared to share volume in 2012. Facebook still accounts for the lion’s share of social photo activity, according to data shared in one slide of the Internet Trends report, but its growth is being supplemented more and more by activity on Instagram, and, to a remarkable degree, on Snapchat. The Snapchat growth is especially surprising, as activity on the semi-private network has easily surpassed that of Instagram in the past two years, and looks on pace to at least double every two months based on past trends.