understanding some words in Pushkin's texts, since relatively few words used by Pushkin have become archaic or changed meaning. In fact, many expressions used by Russian writers of the early 19th century, in particular Pushkin, Mikhail Lermontov (), Nikolai Gogol (), Aleksander Griboyedov (), became proverbs or sayings which can be frequently found even in modern Russian colloquial speech. The political upheavals of the early 20th century and the wholesale changes of political ideology gave written Russian its modern appearance after the spelling reform of 1918. Political circumstances and Soviet accomplishments in military, scientific, and technological matters (especially cosmonautics), gave Russian a worldwide prestige, especially during the mid-20th century. During the Soviet period, the policy toward the languages of the various other ethnic groups fluctuated in practice. Though each of the constituent republics had its own official language, the unifying role and superior status was reserved for Russian, although it was declared the official language only in 1990. Following the break-up of the USSR in 1991, several of the newly independent states have encouraged their native languages, which has partly reversed the privileged status of Russian, though its role as the language of post-Soviet national discourse throughout the region has continued. The Russian language in the world declined after 1991 due to the collapse of the Soviet Union and decrease in the number of Russians in the world and diminution of the total population in Russia (where Russian is an official language), however has since been reversed. According to figures published in 2006 in the journal "Demoskop Weekly" research deputy director of Research Center for Sociological Research of the Ministry of Education and Science (Russia) Arefyev A. L., the Russian language is gradually losing its position in the world in general, and in Russia in particular. In 2012, A. L. Arefyev published a new study "Russian language at the turn of the 20th–21st centuries", in which he confirmed his conclusion about the trend of weakening of the Russian language after the Soviet Union's collapse in various regions of the world (findings published in 2013 in the journal "Demoskop Weekly"). In the countries of the former Soviet Union the Russian language was being replaced or used in conjunction with local languages. Currently, the number of speakers of Russian in the world depends on the number of Russians in the world and total population in Russia. See also List of English words