Turkmenistan's major gas deposits were discovered in its central and eastern areas in the 1940s and 1950s, and in the 1980s the republic became the second largest producer of gas in the Soviet Union, behind the Russian SFSR. During the Soviet era gas was exported mainly to other Soviet republics, as Turkmenistan steadily increased delivery from about 9.2 million m³ in 1940 to about 234 million m³ in 1960 and about 51 billion m³ in 1975. This export was under centralised control, and most of the export revenue was absorbed into the Soviet central budget.