The accompanying article — Microsoft at Middle Age — is now available to non-subscribers. It leads with a Bill Gates quote:
WHAT are you on? The ‘fuck Windows’ strategy?
Thank you, The Economist. And thanks, Kai Riemer, for Friday’s tweet.
Follow Philip Elmer-DeWitt on Twitter at @philiped. Read his Apple (AAPL) coverage at fortune.com/ped or subscribe via his RSS feed.