It seems that in the United States, at least, app developers and advertisers who rely on targeted mobile advertising for revenue are seeing their worst fears realized: Analytics data published this week suggests that US users choose to opt out of tracking 96 percent of the time in the wake of iOS 14.5.

When Apple released iOS 14.5 late last month, it began enforcing a policy called App Tracking Transparency. iPhone, iPad, and Apple TV apps are now required to request users’ permission to use techniques like IDFA (ID for Advertisers) to track those users’ activity across multiple apps for data collection and ad targeting purposes.

The change met fierce resistance from companies like Facebook, whose market advantages and revenue streams are built on leveraging users’ data to target the most effective ads at those users. Facebook went so far as to take out full-page newspaper ads claiming that the change would not just hurt Facebook but would destroy small businesses around the world. Shortly after, Apple CEO Tim Cook attended a data privacy conference and delivered a speech that harshly criticized Facebook’s business model.

Nonetheless, Facebook and others have complied with Apple’s new rule to avoid being rejected from the iPhone’s App Store, though some apps present a screen explaining why users should opt in before the Apple-mandated prompt to opt in or out appears.

This new data comes from Verizon-owned Flurry Analytics, which claims to be used in more than one million mobile apps. Flurry says it will update the data daily so followers can see the trend as it progresses.

Based on the data from those one million apps, Flurry Analytics says US users agree to be tracked only four percent of the time. The global number is significantly higher at 12 percent, but that’s still below some advertising companies’ estimates.

The data from Flurry Analytics shows users rejecting tracking at much higher rates than were predicted by surveys that were conducted before iOS 14.5 went live. One of those surveys found that just shy of 40 percent, not 4 percent, would opt in to tracking when prompted.

Flurry Analytics’ data doesn’t break things down by app, though, so it’s impossible to know from this data whether the numbers are skewed against app tracking opt-in by, say, users’ distrust of Facebook. It’s possible users are being more trusting of some types of apps than others, but that data is not available.