This morning the folks at RankRanger posted on Twitter that over 70% of the page one Google search results listings are HTTPS. Mozcast has their number of Google's top search results with HTTPS being at 78%, so they are somewhat close but not exact because both tools track different keyword sets.
Here is the RankRanger chart:
Here is the Mozcast chart:
HTTPS is a minor ranking boost in Google.
Forum discussion at Twitter.