I checked. Four official GH compilations (Chronicles, Retrospective I, Retrospective II, The Spirit of Radio)
With the exception of Chronicles (released in '90), I find it somewhat disheartening that the compilations (more than likely studio choice over artists' choise though) ignore their 90's work entirely, when they put out three good CDs and scored a decent number of radio hits ("Roll the Bones", "Nobody's Hero", "Animate", "Stick it Out", "Resist" and "Driven")
The live discography (while expansive) is worth checking out as well