According to the HTTP Archive, HTTPS adoption for the top 300K sites has grown by 300%+ over the last two years , from 4% to 13%. However, it's important to keep in mind that HTTP Archive is counting unique origins, which does not account for the popularity of any particular site - e.g. a single origin, like google.com
may be responsible for many more user navigations as compared to a site that you may visit infrequently.
Looking at the number of actual navigations shows that, in Chrome, the number of HTTPS navigations  has grown from ~27% to ~58% within the same period of last two years - i.e. more than half of user navigations are over HTTPS!
The goal is, of course, to get to 100% - aka, HTTPS everywhere - and we still have a lot of work to do as an industry to make this a reality, but we’re making good progress!  http://httparchive.org/trends.php#perHttps - 2012-2014 stats. HTTPS navigation: any navigation (link clicks, omnibox navigations, back/forward, fragment changes, pushState) where the destination scheme of the main frame is “https”.