I remember making a comment in the WT (when the worldwide report was the subject of discussion) to the effect that of the five most populated countries in the world, four were virtually untouched by the WT. It went over like a lead balloon.
In order of population China, India, US, Indonesia, Pakistan. Of these, only the US has a significant representation of JWs, but the five countries together represent about 45% of the world population. At the time I made the comment, China and Indonesia were under ban and didn't appear in the report, at least explicitly by name. Looking at the 2021 report, China is still absent but the other four countries are listed. India, Indonesia, and Pakistan together are showing around 86,000 JWs, compared to the US with 1,256,000. Since China is not listed, I don't know how many JWs are there but it must be less than the 212,000 shown for '33 other lands'.
There are a number of reasons for this that come to mind. One is the effectiveness or lack therof of the Christian missionaries in the preceding centures (1600's-1800's), which laid the foundation for the JWs. Related to this is the prevalence of non-Christian faiths. India, Indonesia, and Pakistan have been remarkably resistant to Western missionaries, including JWs. Government action in the 1900's in China and Indonesia has been significant in keeping the JWs out.