That's all Vandenberg is ever used for aside from missile tests which go west[1], and there would be no reason to use it for launches to the east when you can accomplish those just as easily from Florida without the safety concerns.

[1] http://www.spacearchive.info/vafbview.htm "With the exception of the Pegasus XL, all Vandenberg AFB launches take place from the base. Minuteman III missiles climb rather steeply and head due west. Delta, Taurus, and other satellite launch vehicles fly towards the south and climb more slowly."