How many countries participated in the cricket world cup from 1975 to 2011?

The teams that have played in one or more ODI World Cup tournaments are: Australia, East Africa, England, India, New Zealand, Pakistan, Sri Lanka, West Indies, Canada, Zimbabwe, South Africa, Kenya, Netherlands, United Arab Emirates, Bangladesh, Scotland, Namibia, Bermuda and Ireland. That means 19 teams have played in at least one World Cup. Some of those teams are made up of players from multiple countries like East Africa and the West Indies. Also Scotland and England are two seperate regions of one country called the United Kingdom. All of this means that depending on what you conside a country, the answer could be 15 (as only 15 are one single country) or it could be 19 or it could me heaps more than that.