But:

One billion words?

If all the words in the Oxford English Corpus were laid out end to end (measuring on average 1cm), the total would stretch from London to New York, around 10,000 km. Because the corpus is a collection of texts, there are not one billion different words: the humble word 'the', the commonest in the written language, accounts for 50 million of all the words in the corpus!

http://www.askoxford.com/oec/mainpage/?view=uk