Insert two spaces at the beginning of each line.

Testing (edit, it didn't work when I copied it from the page and added two spaces before each line, see below):

  1 Mosquito 1,000,000
  2 Human 475,000
  3 Snake 50,000
  4 Dog 25,000
  5 Tsetse Fly 10,000

See:

  https://news.ycombinator.com/newsfaq.html

which has a link to:

  https://news.ycombinator.com/formatdoc

I should be more clear. I know how to add verbatim formatting.

I'd like to know if the OP manually aligned the columns in the table, if they used a program to do so, or something els.

Yeah, I had to put some manual effort into this. (I wish I knew a program which could do this kind of thing.)

This might be along the lines of what you are looking for?

https://plaintexttools.github.io/plain-text-table/