Sometimes IE7 statistics based on user-agent strings is unreliable.
We have a phantom measurement of 3% IE7 usage when the actual usage is 0% (our web app prevents IE7 users using JavaScript because it is too broken). The measured IE7 users are actually using IE8 (as a control embedded within a Windows exe, actual usage measured using @cc_on @_jscript_version).
Browsers are getting upgraded in general, but you still get government-x and company-y asking for IE7 support.