17 percent of the worldwide production and 83 percent of Russian production. Of this amount, the Yamburg subsidiary produced 41 percent, Urengoy 23.6 percent, Nadym 10.9 percent, Noyabrsk 9.3 percent and others 15.2 percent. In addition, the company produced 32.28 million tons of oil and 12.07 million tons of gas condensate. The majority of Gazprom's fields are located in the Nadym-Pur-Taz region (near the Gulf of Ob) in Yamalo-Nenets Autonomous Okrug in Western Siberia. Historically, the three largest fields are Medvezhe, Urengoy and Yamburg. After more than twenty years of production, the fields are now in decline. Production from the fields has decreased by twenty to twenty-five bcm per year. The production at Zaporliarnoe, Gazprom's fourth largest field, increased until 2004, offsetting the decline in the other fields. Since 2004, Gazprom has maintained production by activating new smaller fields and by purchasing production assets from other companies. Gazprom Neft produces crude oil. In 2005, Gazprom purchased 75 percent of the Gazprom Neft shares for $13.1 billion. Imports from Central Asia Gazprom's ability to supply natural gas to domestic market and for reexport has relied to a large extent on imports from Central Asia. In 2007, Gazprom imported a total of from Central Asia: from Turkmenistan, from Kazakhstan, and from Uzbekistan. In particular, Gazprom purchased seventy-five percent of Turkmenistan gas exports in order to supply gas to Ukraine. In 2008, Gazprom paid $130/mcm to $180/mcm for gas from Central Asia. Reserves In 2015, Gazprom's proved and probable reserves of natural gas were , a 3.8% increase from the 2011 figure which represented 18.4% of the world's reserves. In 2015, the reserves of crude oil were 1.355 billion tons and the reserves of gas condensate were 933.3 billion tons. 59.8 percent of Gazprom's natural gas reserves (Categories A+B+C1) were located in the Urals Federal District (decreasing), 20.5 percent in the Arctic shelf (increasing), and 8.3 percent in the Southern Federal District and North Caucasus Federal District. Development and exploration Gazprom has invested about 480 billion rubles ($20 billion) in new major projects in order to maintain supply. Nearly 37 percent of Gazprom's reserves are located in the Yamal Peninsula and in the Barents Sea. Blue Stream Pipeline One of Gazprom's major projects is the Blue Stream Pipeline. The Blue Stream Pipeline delivers natural gas to Turkey via the Black Sea. In 1997, the Blue Stream Pipeline agreement between Turkey and Russia was