Supposedly there are millions of W7 bots, so NetMarketShare has retconned their data to strip market share from W7.
It makes no sense.
Bots need a machine to run on and they are visiting sites, so therefore they are actually part of the market.

It's like the Transportation Department saying, "since 5% of vehicles on the road are stolen, we are removing them from the road congestion statistics."

Here is the retconned info for last 6 months:
If you visit the site, you'll notice that the data points on the graph do not match the info listed in the table.

This reminds me of the NetMarketShare XP fiasco from a couple of years ago.