Read the following passage and mark the letter A, B, C, or D on your answer sheet to indicate the correct answer to each of the questions. 

Over the past 600 years, English has grown from a language of few speakers to become the dominant language of international communication. English as we know it to day emerged around 1350, after having incorporated many elements of French that were introduced following the Norman invasion off 1066. Until the 1600s, English was, for the most part, spoken only in England and had not expanded even as far as Wales, Scotland, or Ireland. However, during the course of the next two century, English began to spread around the globe as a result of exploration, trade (including slave trade), colonization, and missionary work. Thus, small enclaves of English, speakers became established and grew in various parts of the world. As these communities proliferated, English gradually became the primary language of international business, banking, and diplomacy.

Currently, about 80 percent of the information scored on computer systems worldwide is in English. Two thirds of the world's science writing is in English, and English is the main language of technology, advertising, media, international airport, and air traffic controllers. Today there are more than 700 million English users in the world, and over half of these are non-native speakers, constituting the largest number of non-native users than any other language in the world.

According to the passage, approximately how many non-native users of English are there in the world today ?