The Intel 80386 was released in 1985, but was initially expensive, and took a long time to fully displace the earlier 80286 from the market; subjectively, I remember significant numbers of 286 machines around into the early nineties. Of course, the 286 remained cheaper for a long time. And it wasn't until the release of Windows 3.0 in 1990, that a typical desktop user would really gain much benefit from a 386.
In what year did the 386 first sell more units than the 286?
I would also be interested in crossover years for dollar sales, and units and dollars of installed base, but unit sales seems likely to be the easiest to establish unambiguously, so that's my primary question.