If it comes to population, needless to say, China is a foremost country making up a quarter of global population.
This sentence is not written well, but it does demonstrate great understanding of the expression "needless to say" and also great understanding of the adjective "foremost".
The sentence is too long, and it uses too many words to express a simple idea. To write well, express ideas in fewer words.If something is "needless to say", then it probably is not useful to include it in your paper. After all, it is needless lol. : ) So you can type:
China's population comprises a quarter of the global population. Needless to say, [type something interesting here...]
North America is dominating the list of prosperous countries forming the 35% of global wealth.
This is great. It will be clearer if you put a, after the word "countries".
The point you are making is an interesting one, and it will keep the reader's attention. I just think you can make the first sentence much better. The first sentence should make the reader feel a sense of curiosity. It's great if you can type the first sentence with words that surprised the reader in some way. The first sentence of the first paragraph is like your left hand reaching out and putting your opponents guard in check, and the thesis statement at the end of the first paragraph is like a big right cross that catches him square in the nose and knocks him out of the ring. That probably is not a good explanation,lol. Here is a better one:
read that first paragraph again and ask yourself what is the reason it is important, and what is the reason it might be important to the person reading the essay or to any person. Type a sentence about that; make it an interesting sentence, and add it to the beginning of this first paragraph.