Ron's advice is that "whenever you use a parallel structure with omitted/elided words, the EXACT omitted word(s) MUST be present, IN PARALLEL STRUCTURE, elsewhere in the sentence. this means in exactly the same form - no alterations, no tense changes, no nothing. "
My question then is regarding these followings sentences:
People in China are taller than Spain.
(People in China are taller than [people in] Spain.)
Gas prices in 2007 are higher than in 1997
(Gas prices in 2007 are higher than [gas prices] in 1997)
Consumption accounted for more than half the GDP in the 90's, a greater proportion than in any other decade.
(greater proportion than [the proportion] in any other decade.)
My gut tells me that the first sentence is wrong as it illogically compares people in China and Spain itself. I intuit however that the second and third sentences are correct. What then are the differences among these three sentences? All of them fall under Ron's advice mentioned above.