I am looking for market shares of software platforms from 1989 to
2002. Platforms are categoried as follows:

1. Apple. All versions of Apple computers.
2. Unix. All variants of Unix, such as Sun Solaris and Linux.
3. Windows. All versions of DOS and Windows (3.1/95/98/2000/ME/NT/XP).
4. OS/2 mini computers and mainframes.
5. Others. 
 
Of course, please feel free to break each category into
sub-categories. Basically, I am looking for one pie chart for each
year. Market share can be measured by number of users or revenues.

Software_researcher:

For numbers that detailed over a 14-year period, you'll want to
contact either IDC or Gartner Group, both of which have monitored
overall market shares:
www.idc.com
http://www4.gartner.com/Init

Expect access to summary software numbers to be $3,000 to $6,000 and
current reports won't cover all 14 years. However, once you're a
client, you can have the additional years covered from their library
-- or visit the library yourself to fill in the extra data.

Best regards,

Omnivorous-GA