Is that including people who immigrated or only those who grew up there? Your link [0] mentions "residents" throughout, which implies that it's counting Chinese people who moved to Singapore as adults. I've known a decent number of Singaporeans, including many ethnically Chinese Singaporeans I met while working in Beijing, and I've never met a single person who grew up there and can't read English.
If adult immigrants are included, then I strongly agree with the later part of your comment! There's no reason the US shouldn't similarly be included in the list as it has tens of millions of Spanish-speaking residents who immigrated as adults. Canada, Australia and New Zealand should probably be included too, if Singapore is.
I also assumed it was including mainland Chinese immigrants, especially since the rate of Chinese only is so much higher than Malay only and Tamil only. Lots of wealthy Chinese move to Singapore every year. (A bit different from immigration in the US.)
If adult immigrants are included, then I strongly agree with the later part of your comment! There's no reason the US shouldn't similarly be included in the list as it has tens of millions of Spanish-speaking residents who immigrated as adults. Canada, Australia and New Zealand should probably be included too, if Singapore is.