† "PIAAC" stands for the OECD’s Programme for the International Assessment of Adult Competencies. Countries are ranked in descending order of the combined percentage of adults scoring at Level 3 and Level 4/5. Values for each country do not add up to 100%, because some adults were not able to provide enough background information to impute proficiency scores because of language difficulties, or learning or mental disabilities. Information regarding the statistical significance of the observed differences between countries with respect to the percentage of their populations scoring at particular levels was not available from data collector when this indicator was prepared. The difference between the mean U.S. literary proficiency score and that of every other participating country, with the exception of France, is statistically significant at the .05 level. The difference between the U.S. average and the combined average for all participating countries is also statistically significant.
* The sample for the Russian Federation does not include the population of the Moscow municipal area.
** Area under the effective control of the government of the Republic of Cyprus.
Source: Organisation for Economic Co-operation and Development (OECD), OECD Skills Outlook 2013: First Results from the Survey of Adult Skills (Paris: OECD Publishing, 2013), Table A2.1.