I'm not sure if they support that, I looked for that myself, but couldn't find it. A way of going around it is to create labels on multiple axis. e.g. is below:
<https://chart.googleapis.com/chart?chxt=x,y,r,x&chxl=0:%7CJan%7CJuly%7CJan%7CJuly%7CJan%7C1:%7C0%7C50%7C100%7C2:%7CA%7CB%7CC%7C3:%7C2005%7C2006%7C2007&cht=lc&chd=s:cEAELFJHHHKUju9uuXUc&chco=76A4FB&chls=2.0&chs=200x125> URL https://chart.googleapis.com/chart?chxt=x,y,r,x&chxl=0:|Jan|July|Jan|July|Jan|1:|0|50|100|2:|A|B|C|3:|2005|2006|2007&cht=lc&chd=s:cEAELFJHHHKUju9uuXUc&chco=76A4FB&chls=2.0&chs=200x125 -- You received this message because you are subscribed to the Google Groups "Google Chart API" group. To post to this group, send email to [email protected]. To unsubscribe from this group, send email to [email protected]. For more options, visit this group at http://groups.google.com/group/google-chart-api?hl=en.
