Diamond White was used on both the facelift and pre-facelift from January 2005 to August 2006.
Frozen White was used on all ST's after this, until they ceased production in 2008.
I don't have the figures, but I'd be shocked if there were twice as many pre-facelifts around. They were only sold from January to early autumn 2005, whereas the facelift was sold for over three years.