Actually, the number is ever so slightly higher than 100,000 words per year, but this number makes the math easy to grasp and demonstrates the magnitude of the problem that leads to a huge gap in achievement.
In their entire educational careers, reluctant and non-proficient readers do not read as many words as our proficient readers are exposed to in a single year. The gap between proficient and non-proficient readers grows with every day, every month and every year. Early readers consume more books, but I was unable to find any research that attempted to estimate how many words children are being exposed to as they read picture books and early chapter books. Ten years estimates student reading from eight years through eighteen years of age. The estimates are rough, yet still profound taken from even the most conservative interpretation.