According to Google’s latest transparency report released Tuesday, encryption protected 77 percent of requests sent from computers around the world to Google’s servers, as of Feb. 27, an improvement from 52 percent at the end of 2013.

This data covers most Google traffic, with the exception of YouTube. Google said it is working towards achieve 100 percent encryption across all its products and services.

Gmail is 100% encrypted, as is Google Drive, which is not a surprise since Gmail is HTTPS-only since March 2014. Maps, Finance, News and Advertising are all above 50%, with the last two showing a huge increase in the last two years. As Google explains in the report, HTTPS “relies on encryption—SSL or TLS—to secure the connection,” and offers protection against “eavesdroppers, man-in-the-middle attacks, and hijackers who attempt to spoof a trusted website.”

“We are working to implement HTTPS across all of our products,” the company said. “We continue to work through the technical barriers that make it more difficult to support encryption on some of our products.”

Google also notes that the “vast majority” of unencrypted end user traffic comes from mobile devices, largely because some older devices cannot support modern encryption, standards,  or protocols. “Unfortunately, these devices may no longer be updated and may never support encryption,” Google wrote in the report.

Encryption also varies by country, “due to a variety of factors, including the types of devices in use in that country, as well as the availability of software that can support modern TLS,” Google said.

Several other “technical and political challenges” are standing in the way of Google’s goal to attain full traffic encryption, including countries that “block or otherwise degrade HTTPS traffic,” and a lack of technical resources within some organizations to implement it.