I used Google Trends to see how Obama fared compared to Hillary in 2007 from April through December and then how Bernie Sanders did in the same time frame, in 2015 from April through December, in terms of search traffic. Bernie Sanders actually looks like so far, he's done better than Obama. (The search was for ALL, limited to the USA)
Wikipedia explains Google trends:
...shows how often a particular search-term is entered relative to the total search-volume across various regions of the world, and in various languages. The horizontal axis of the main graph represents time... and the vertical is how often a term is searched for relative to the total number of searches, globally.
Clik here to view.

Clik here to view.

And here's what we have so far-- December through January 13th for Clinton and Sanders. Remember, though the graph is the same width as above, the date range is only 44 days.
Clik here to view.

Again, Bernie is the red line. My read is that Bernie Sanders has been doing better in this election cycle against HIllary than Obama did in 2007, 2008 And the trend looks awesome. What’s your read?
reprinted, with updates, from OpEdNews.com