Of the 101m iPhones currently in use in the US, over 60 per cent are an iPhone 6 or higher.

According to CIRP figures, at the end of September 2015, there were 58m iPhone 6 and 6 Plus handsets in use, and 4m 6S and 6S Plus. Notably, the latter was only available for a single weekend during the measured one-quarter period.

Notably, those are the four Apple handsets with Apple Pay capabilities, meaning the payment services potential user base is equivalent to nearly a fifth of the entire US population.

The overall iPhone install base grew four per cent during the quarter – considerably slower than the same quarter in 2014, when it grew six per cent, and the average over the past two years, eight per cent.

“The data again shows that growth in the installed base of iPhones in the US has slowed,” said CIRP co-founder and CEO Josh Lowitz. “In previous quarters, we saw the installed base grow by as much as 17 per cent, in the December 2013 quarter after the launch of the iPhone 5S and 5C. As the US market matures, Apple has fewer firsttime smartphone buyers to add to their base, and faces the challenge of attracting loyal Android users.”