Apple shared its traditional first weekend iPhone gloat yesterday and sales of 13 million iPhone 6s and 6s Plus devices indicate its position in the smartphone market is as strong as ever.

“Sales for iPhone 6s and iPhone 6s Plus have been phenomenal, blowing past any previous first weekend sales results in Apple’s history,” said Tim Cook, Apple’s CEO. “Customers’ feedback is incredible and they are loving 3D Touch and Live Photos, and we can’t wait to bring iPhone 6s and iPhone 6s Plus to customers in even more countries on October 9.”

This performance is especially impressive when you consider the latest iPhone versions were more of a tweak on the previous generation, rather than anything revolutionary, but that could be as much a consequence of the postpaid upgrade cycle, which has a two year cadence.

The chart below is derived from iPhone gloat press releases for the past six years. As you can see the underlying trend is for Apple to increase its first weekend sales by around 2 million units each year. But it alternates between small increases and large increases, with this year being a relatively large one.

This trend was probably set by the decision two launch two new phones simultaneously for the first time in 2013, with the 5s and 5c (although the latter was just a tarted-up version of the year-old model), which resulted in a four million unit jump in first weekend sales. With so many iPhone users having upgraded the previous year, the genuinely innovative launches of the 6 and 6 Plus only yielded a one million increase and it’s likely that a large proportion of those who bought a 5s or 5c waited until their 24 month postpaid contracts came up for renewal this year to upgrade.

Regardless, at a time when nearly all its competitors are struggling to even maintain their sales, Apple’s sales momentum seems unstoppable and at margins all the other smartphone makers can only dream of. While the Apple brand remains all-powerful, this continued growth is as much a product of practical things like supply chain, distribution and logistics, which are Tim Cook’s strengths.