Thanks for looking it up. I also found the blancco study, but their score includes "crashing apps, WiFi connectivity and other performance issues" so it seems more like a consumer satisfaction survey than a device reliability study.
The squaretrade thing is more interesting, the raw data for the statista link is https://www.squaretrade.com/htm/pdf/iPhone_failure_rates_6_2.... I'd be interested in an update on that, phone materials have changed a lot in the last six or seven years. I would hope that things have improved overall but it would be nice to get confirmation on that.
I only found software rates https://www.blancco.com/resources/rs-state-of-mobile-device-... though I know nothing of the veracity of this ... study.
https://www.statista.com/statistics/218777/failure-rates-for... ..
Ah, finally something a bit more relevant: https://www.squaretrade.com/cell-phone-comparison-study-nov-... 2% for iPhone 4.