The history of the origin and transformation of the ISSN Register is considered, and all publications available through Google Scholar and Semantic Scholar on the number of ISSN records and their dynamics are collected together. Data on the number of entries in the ISSN Register by country for 2014 and 2021 is presented, along with the seven-year increase in these entries in comparison with similar data for 1991 through 1998. From these data, the top ten countries were analyzed based on the maximum increase in records over these two seven-year periods. It is shown that the first list of countries with the maximum increase in the number of ISSN records for 2014 through 2021 included exclusively developing countries, and the second list (1991–1998) included mainly developed countries. Similar increases in the number of ISSN records were analyzed for the languages of serial publications and it was shown that in both language lists there was only the Turkish language and the leading European languages were absent. It is shown that the total contributions of ISSN records of leading countries and languages to the total number of ISSN records satisfy the Pareto principle for all years studied. The calculations were made on the indices of linguistic liberalization of the information space of states and information and linguistic influence (or language expansion) according to ISSN indicators. It is shown that aggregating countries by language has made it possible to significantly reduce the discrepancy between the total ISSN records for countries in which a particular language predominates and the ISSN records for a given language. These differences for calculations for 2014 and 2021 levels did not exceed 9% for English, Spanish and Portuguese, and 14% for French, which corresponds to the languages of former colonial empires. In conclusion, a linear regression relationship between ISSN/10 thousand people and GDP per capita with moderate values of the correlation coefficient was obtained in two versions, which indirectly confirms the Constancy Hypothesis.