Who are the primary target audience now and has this changed? Who was it before and how do you know?

Text: 
Facebook


Current target audience:
13-34 year olds


Original target audience:
18-24 year olds
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Text:
Twitter


Current target audience:
18-34 year olds


Original target audience:
25-44 year olds
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Text:
Google+


Current target audience:
13+


Original target audience:
18+