OPEC HQ

I don't really have anything important to say, but why is the headquarters for the Organization of Petroleum Exporting Countries in Vienna, Austria? Okay here are the countries in OPEC: Algeria, Angola, Iraq, Indonesia, Iran, Kuwait, Lybia, Nigeria, Qatar, Saudi Arabia, United Arab Emirates, and Venezuela.

Here's a map of the OPEC countries.

Here's another map of the OPEC countries with a big red X on Vienna.

I'm all for asking "why not?" but it just seems strange. I guess in a way it makes sense not to use a city anywhere in the cartel. And I'd be all for Vienna, too.