A quite a good resource is imho the standard clock setting in Microsoft Windows installations:
image from talkstandards.com
As you can see, it’s particularly North America, India, the Philippines, Colombia, Egypt, Saudi Arabia, and Australia
This is more or less confirmed by Wikipedia that states that
in most English-speaking regions, particularly the United States, the
Philippines and the United Kingdom and its former colonies, the
12-hour clock is the predominant form of stating the time.
Credit:stackoverflow.com‘