Alexa is hooked on a new book series, The Galaxy. Each book in the series is the same length and chronicles a different year in the Waka Waka Galaxy. Alexa has cleared off the top shelf of her bookcase to leave room for each of the books as they come out. There is a proportional relationship between the number of books on the shelf, x, and how much shelf space the books take up (in inches), y.
The equation that models this relationship is y=2x.
How many books will take up 16 inches of shelf space? Write your answer as a whole number or decimal.