The 2011 bubble was ~3000% (from $1 to $32), the early 2013 bubble was ~1500% (from $13 to $260), and only the last rally was 600% (from $200 to $1200).
For a while this ballpark scenario seemed plausible but now I don't think a continuation of it accounts for S-curve adoption, should that happen. Would be interesting if the U.S. kept DPR's coins instead of auctioning so they could bootstrap U.S. gov exchanges: http://www.bloomberg.com/video/can-bitcoin-save-the-post-office-iQx5kWnzQI~iWL2ZmNNm0A.html