Demographics feed URL is available from Event Settings / Feeds section. Content is updated regularly (at least once a minute) and has this format:
{"rounds": [{"round": "affectionate","segments": [{"name": "location","values": [{"value": "wales","data": {"count": "1","sum": "24"}},{"value": "london","data": {"count": "1","sum": "36"}},{"value": "wm","data": {"count": "1","sum": "23"}},{"value": "em","data": {"count": "3","sum": "81"}},{"value": "nw","data": {"count": "1","sum": "32"}},{"value": "ee","data": {"count": "1","sum": "27"}},{"value": "yorks","data": {"count": "2","sum": "69"}}]},{"name": "age","values": [{"value": "18-24","data": {"count": "1","sum": "39"}},{"value": "25-34","data": {"count": "6","sum": "168"}},{"value": "35-44","data": {"count": "3","sum": "85"}}]},{"name": "animal","values": [{"value": "bird","data": {"count": "1","sum": "23"}},{"value": "dog","data": {"count": "4","sum": "108"}},{"value": "snake","data": {"count": "2","sum": "67"}},{"value": "cat","data": {"count": "3","sum": "94"}}]},{"name": "newspaper","values": [{"value": "ft","data": {"count": "2","sum": "59"}},{"value": "guardian","data": {"count": "2","sum": "51"}},{"value": "knitting","data": {"count": "1","sum": "39"}},{"value": "sun","data": {"count": "5","sum": "143"}}]},{"name": "gender","values": [{"value": "female","data": {"count": "5","sum": "155"}},{"value": "male","data": {"count": "5","sum": "137"}}]}]},{"round": "Total","segments": [{"name": "location","values": [{"value": "wales","data": {"count": "1","sum": "0"}},{"value": "london","data": {"count": "1","sum": "0"}},{"value": "yorks","data": {"count": "2","sum": "0"}},{"value": "em","data": {"count": "3","sum": "0"}},{"value": "ee","data": {"count": "1","sum": "0"}},{"value": "nw","data": {"count": "1","sum": "0"}},{"value": "wm","data": {"count": "1","sum": "0"}}]},{"name": "newspaper","values": [{"value": "sun","data": {"count": "5","sum": "0"}},{"value": "ft","data": {"count": "2","sum": "0"}},{"value": "knitting","data": {"count": "1","sum": "0"}},{"value": "guardian","data": {"count": "2","sum": "0"}}]},{"name": "age","values": [{"value": "25-34","data": {"count": "6","sum": "0"}},{"value": "18-24","data": {"count": "1","sum": "0"}},{"value": "35-44","data": {"count": "3","sum": "0"}}]},{"name": "animal","values": [{"value": "cat","data": {"count": "3","sum": "0"}},{"value": "bird","data": {"count": "1","sum": "0"}},{"value": "snake","data": {"count": "2","sum": "0"}},{"value": "dog","data": {"count": "4","sum": "0"}}]},{"name": "gender","values": [{"value": "male","data": {"count": "5","sum": "0"}},{"value": "female","data": {"count": "5","sum": "0"}}]}]}]}
​