In mid-December Google began indexing HTTPS by default and you can see that it has been at about 25% since then, with a steady and small increase over time.
HTTPS: URLs are currently right around 25% of page-1 results in the MozCast 10K.— Dr. Pete Meyers (@dr_pete) January 12, 2016
It doesn't necessarily mean that HTTPS is ranking better in Google, although there is an HTTPS ranking boost, it just means that Google is showing more HTTPS URLs in the top ten. Some of those might be HTTP URLs but Google is showing the HTTPS version because they work.
I did ask Zineb if there have been any changes with that since the HTTPS default announcement and she said no:
Forum discussion at Twitter.