We would like to know two things:
1. How do new words appear in the book?
2. What percent of the book is written with the words that appear page by page?On the following plots, the horizontal axis denotes the page number. The green line on the plots below answers the first question. It shows what percentage of unique words appeared to this page. The blue line answers the second. It shows how much of the book is written with the words that appeared on this page or earlier.
Results
The Secret Adversary is an average length book. It is 250 pages with exactly 75208 words. Each word in average appears 14 times, what gives us 5248 unique words in the book.
You will know 90% of words after 40 pages which are 16.00% of the book.