fiddle - http://jsfiddle.net/z8fw7/
When I hover over the column I can see this weird big number, where is it coming from.
If I add one more date entry. e.g
[Date.UTC(2010,2,31), 28.84],
[Date.UTC(2011,2,31), 28.84],
[Date.UTC(2012,2,31), 32.65]
The tooltip then displays the proper year value as expected. It works flawlessly with 3 data values while it does not work with 2 data values. How can I make sure that it works with even 2 data values.