Ill take any numbers from a site that says apple is only at three and three quarters with a very large grain of salt.
That combines with the news that Dell has not only started selling Linux desktops (Ubuntu) but growing their desktop line compounded with HP (Red Hat) growing their desktop line as a sign that Linux is doing just fine in the market place. Will it ever be a dominate force? probably not but it will maintain a healthy enough market share to keep the community interested in development.
Even if the site was completely to be trusted than the Linux market share has grown by seven percent over its may numbers (1.25 to 1.34).
Thanks.
You can stick your head back in the sand if you want, but other well known web counters such as w3schools show Linux use actually declining, not just stalled like this one did.