The phrase "a significant fraction of users" is correct and usable in written English.
It can be used when discussing a notable portion of a user base in contexts such as surveys, studies, or user feedback.
Example: "In our recent survey, a significant fraction of users reported that they prefer the new interface over the old one."
Alternatives: "a considerable percentage of users" or "a notable share of users".
More recently, Bonneau et al. [4] analyzed a real-world data set on security questions of millions of Google account holders and they found that a significant fraction of users (40%%) were unable to recall their answers when needed.
The outcomes of this study is that the publication of anonymized location data in its original format, i.e. at the sector level or cell level, put at risk the user privacy because a significant fraction of users can be re-identified from the anonymized data.
(As we will see in Section 5, the downlink SINR distribution under universal reuse results in a significant fraction of users falling below the SINR required to achieve the minimum rate. We consider frequency reuse because it improves the SINR distribution so that fewer users are below this critical SINR value).
Even if password policy objects are used to force users not to pick trivial passwords, dictionary attacks can sometimes be successful against a significant fraction of the users in a realm.
We hypothesize that users with a significant fraction of tweets about their private, daily lives provide better data for now-casting than more reserved users.
Social media is increasingly becoming a significant fraction of the content retrieved daily by Web users.
I know a lot of people who swear by Google's own spam filters, but I'm privacy conscious enough that I'm loathe to give my whole email corpus to Google (though I correspond with so many Gmail users that Google already has a significant fraction of my email output in its servers).
Given that Facebook reaches 680 million users every day on mobile devices, it really isn't surprising at all that a significant fraction of top developers are testing this out.
