Looking at the overall picture in this CMB Consumer Puls 2010 Report, it seems all clear: eMail leads with 86%, Facebook comes second with 49%, Phone third with 25 % ... Twitter sixth with 5 %.
But it looks quite different, when you break down used content sharing tools by age group (and gender)
Unfortunately, the question „When you share content, how do you typically share it with your peers, within your age group“ has not been asked. But we can guess ...
From the report:
How, Why, and What Content People Share Online
by Josh Mendelsohn and Jeff McKennaChadwick Martin Bailey
Download full report (29 pg., PDF, September 2010)
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Earlier from CMB:
Why people become fans and followers of a brand - Social Media Matters