What is the fine-grained topic of the following text: Over the coming two to three decades some 3 billion people in Asia, Middle-East & Africa, Latin-America will join the new global middle-class and are prognosed to enjoy the same consumption patterns in their homes, in their offices and in their transportation now so much taken for granted in the OECD and upper middle class families in the emerging and developing nations. Only return the topic.
Growth of the global middle-class and changing consumption patterns in developing nations