Surprisingly, I have not been able to find the answer to this. I believe there are 24 teams in Canada alone. It's easy to come across Top Tens and even world league tables, but as for the total number of teams worldwide, I have drawn a blank. Perhaps this is because 'hockey' can be applied to the US game, or the field hockey started in the UK or ice hockey which has prominence in fiercely cold countries as you might expect.
And, in fact, I'm not sure whether your question was hockey as a whole, or the hockey you know whcich might be any of the three above. In Britain a world championship is being prepared and the countries involved are India, Bulgaria,Slovakia Latvia, Canada, USA Finland, and Hungary