Functional illiteracy
In the US, 14% of adults are  at the "below basic" level for prose literacy; 12% are at the "below  basic" level for document literacy; and 22% are at that level for quantitative literacy. Only 13% of the population is proficient in these three areas. In the terms of the study, "proficient" means these people are able to compare viewpoints in two editorials. They can interpret a table about blood pressure, age, and physical activity. They can also compute and compare the cost per ounce of food items.