to-clause modifer?

[KSSEEJ]

"As post-war “baby-boomers” approach retirement age, our population aged 65 or above is expected to surge from about 900 000 at present to 2.1 million by 2030 to account for a quarter of our population"




Does the underlined to-clause function as a post-modifier, modifying the noun phrase "2.1million"?


Can I rewrite it to ".....2.1 million by 2030, which account for a quarter of our population" or .....2.1 million by 2030, accounting for a quarter of our population" to produce the same meaning of the original sentence?

[Raymott]

"As post-war “baby-boomers” approach retirement age, our population aged 65 or above is expected to surge from about 900 000 at present to 2.1 million by 2030 to account for a quarter of our population"




Does the underlined to-clause function as a post-modifier, modifying the noun phrase "2.1million"?


Can I rewrite it to ".....2.1 million by 2030, which account for a quarter of our population" or .....2.1 million by 2030, accounting for a quarter of our population" to produce the same meaning of the original sentence?

I'd write "... 2.1 million by 2030 and will account for a quarter of our population."
This means that the population aged over 65 will surge to account for a quarter of the population by 2030.