Functional illiteracy consists of reading and writing skills that are inadequate "to manage daily living and employment tasks that require reading skills beyond a basic level". Those who read and write only in a language other than the predominant language of their environs may also be considered functionally illiterate. Functional illiteracy is contrasted with illiteracy in the strict sense, meaning the inability to read or write simple sentences in any language. The characteristics of functional illiteracy vary from one culture to another, as some cultures require more advanced reading and writing skills than do others. In languages with phonemic spelling, functional illiteracy might be defined simply as reading too slowly for practical use, an inability to effectively use dictionaries and written manuals, and other factors. Sociological research has demonstrated that countries with lower levels of functional illiteracy among their adult populations tend to be those with the highest levels of scientific literacy among the lower stratum of young people nearing the end of their formal academic studies. This correspondence suggests that the capacity of schools to ensure students attain the functional literacy required to comprehend the basic texts and documents associated with competent citizenship contributes to a society's level of civic literacy. A reading level that might be sufficient to make a farmer functionally literate in a rural area of a developing country might qualify as functional illiteracy in an urban area of a technologically advanced country. In developed countries, the level of functional literacy of an individual is proportional to income level and inversely proportional to the risk of committing certain kinds of crime. In Russia, where more than 99% percent of the population is technically literate, only one-third of high school graduates can comprehend the content of scientific and literary texts, according to a 2015 study. The UK government's Department for Education reported in 2006 that 47% of school children left school at age 16 without having achieved a basic level in functional mathematics, and 42% fail to achieve a basic level of functional English. Every year, 100,000 pupils leave school functionally illiterate in the UK. In the United States, according to Business magazine, an estimated 15 million functionally illiterate adults held jobs at the beginning of the 21st century. According to the National Center for Educational Statistics in the United States: About 70% of adults in the U.S. prison system read at or below the fourth-grade level,