Apple (AAPL) CEO Tim Cook often says about the company’s iOS devices that it is selling them as fast as it can make them.

In that context, the chart published Tuesday by Piper Jaffray’s Gene Munster illustrates what may be Cook’s most impressive achievement as COO: The rate at which he has been able to ramp up production.

Five years ago, it took Apple 74 days to build — and sell — the first 1 million iPhones.

Last year, for the launch of the iPhone 4S, the company was able to supply 4 million units for the first weekend and build more than 24 million within the first three months.

Last Friday, at least 3 million new iPads were ready for sale in 10 countries, with more on their way to 25 additional countries this coming Friday. Meanwhile, Apple is still building iPhones and iPods by the millions.

That’s a lot of work for those Chinese assembly lines.