New numbers show that the Apple iPhone 6 and iPhone 6 Plus have achieved significant penetration into the U.S. market.

According to Consumer Intelligence Research Partners (CIRP), there are approximately 94 million total iPhones in the United States. Of those 94 million, CIRP found 25 million iPhone 6 and 13 million iPhone 6 Plus models, equating to a 40 percent penetration rate.

It wasn't too long ago that Apple CEO Tim Cook declared during an investor call that there was still a significant amount of consumers who hadn't upgraded to the iPhone 6 or iPhone 6 Plus. According to CIRP numbers, there are still 56 million potential upgrades, a number that is surely to dwindle as more make the switch in the coming months. Around 8 million are still using the much older iPhone 4S and 26 million are using the 18-month-old iPhone 5S.

"We're seeing a higher rate of people switching to iPhone than we've experienced in previous cycles," Apple CEO Tim Cook said of the March quarterly results. "We're off to an exciting start to the June quarter with the launch of Apple Watch."

The iPhone 6 and iPhone 6 Plus helped rejuvenate Apple in a smartphone playing field where many were beginning to criticize the company for stagnating. With larger screens and rounder design, the iPhone 6 and iPhone 6 Plus provided Apple with a significant boost, instantly becoming a hit and helping iOS surge against Android. According to CIRP, Apple sold around 38 million iPhone 6 and iPhone 6 Plus units between the flagships' launch in September 2014 and March 31, 2015. Compare that with the 18-million iPhone 5S unit sales during the same period.

Apple recently reported a favorable March quarter, posting earnings of $13.6 billion, or $2.33 per share and a revenue of $58 billion. The figures represent a 33 percent increase from the same time period last year. Apple also revealed that it shipped 61 million smartphones during the quarter, translating to 40 percent more than the 43.7 million it reported for last year's second quarter.

In other Apple news, the company has finally released a dock for devices with a Lightning port, which means iPhone 5 and up owners finally have a piece. Why Apple waited a few years before releasing a Lightning dock? Nobody knows, but the simply designed piece retails for $40 in the United States, although prices do vary by country.

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