Apple sold more iOS devices in 2011 than it has sold Macs in the last 28 years.

Asymco's Horace Dediu made the observation on the analysis firm's blog this week, illustrating the point in a graph (below).

The iOS platform as a whole reached 316 million cumulative units at the end of last year, Dediu points out, with the first iPhones going on sale in mid-2007.

Analysis: Halo effect moves from iPod to iPhone

However, 28 years after the launch of the first Macintosh, Apple has only reached the 122 million sales mark for the Mac.

"The iOS platform overtook the OS X platform in under four years and more iOS devices were sold in 2011 (156 million) than all the Macs ever sold (122 million)," Dediu wrote.

Dedui made the observation in reference to Apple CEO Tim Cook's observation on iPad sales -- 55 million since the first iPad lanched -- made at a conference earlier this week. (Apple CEO Tim Cook at the Goldman Sachs Technology and Internet Conference -- edited transcript.)

"This 55 [million] is something no one would have guessed. Including us. To put it in context, it took us 22 years to sell 55 million Macs. It took us about 5 years to sell 22 million iPods, and it took us about three years to sell that many iPhones. And so, this thing is, as you said, it's on a trajectory that's off the charts," Cook said.