Formal usage of "than",help?

[lisiyin]

"Soaring television costs accounted for more than half the spending in the

presidential campaign of 1992, a greater proportion than it was in any

previous election."

Can I take "it was" away in vey formal written English or is the usage of "it was" correct or not here?

perhaps, "it" should be replaced by "they" to refer to "costs"?

Thanks

[mykwyner]

The sentence is just fine without "it was." In fact, it is the best choice.