Thanks but i am binding to dynamic data. Problem is as soon as you group, the size of bubbles are compared only within that single serie or group and not against other series.
I want each bubble size to be compared against every other single bubble, no matter in which group or series the bubbles belong.
Use only small numbers for 2011 and high numbers only for 2012, keeping the same maxsize for the bubbles and you will see. the size for the small numbers for 2011 is not relative with the high numbers on 2012