Question: In what year did the country where the manufacturer of the Air Express is located finally adopt Daylight Savings Time?

full_context: Document 1: IAI Scout: The IAI Scout (known in Israel under its Hebrew name זהבן - "Oriole") is a reconnaissance unmanned air vehicle developed in Israel in the 1970s by Israel Aircraft Industries as a competitor to the Tadiran Mastiff. During the 1970s, the Israeli military was becoming increasingly interested in battlefield UAVs, and in response IAI management finally decided that they were interested in the concept as well. The Scout had a similar configuration as the Mastiff, with a pusher propeller and a twin-boom tail.
Document 2: Daylight saving time: After Germany led the way with starting DST (German: Sommerzeit) during World War I on 30 April 1916 together with its allies to alleviate hardships from wartime coal shortages and air raid blackouts, the political equation changed in other countries; the United Kingdom used DST first on 21 May 1916. US retailing and manufacturing interests led by Pittsburgh industrialist Robert Garland soon began lobbying for DST, but were opposed by railroads. The US's 1917 entry to the war overcame objections, and DST was established in 1918.
Document 3: Lockheed Air Express: The Lockheed Air Express was the second aircraft design created by the Lockheed Aircraft Company after its founding in 1927; the type first flew in April 1928.
Document 4: United States Air Force: The fighter aircraft of the USAF are small, fast, and maneuverable military aircraft primarily used for air-to-air combat. Many of these fighters have secondary ground-attack capabilities, and some are dual-roled as fighter-bombers (e.g., the F-16 Fighting Falcon); the term "fighter" is also sometimes used colloquially for dedicated ground-attack aircraft. Other missions include interception of bombers and other fighters, reconnaissance, and patrol. The F-16 is currently used by the USAF Air Demonstration squadron, the Thunderbirds, while a small number of both man-rated and non-man-rated F-4 Phantom II are retained as QF-4 aircraft for use as Full Scale Aerial Targets (FSAT) or as part of the USAF Heritage Flight program. These extant QF-4 aircraft are being replaced in the FSAT role by early model F-16 aircraft converted to QF-16 configuration. The USAF has 2,025 fighters in service as of September 2012.
Document 5: Daylight saving time: Starting on 30 April 1916, Germany and its World War I ally Austria-Hungary were the first to use DST (German: Sommerzeit) as a way to conserve coal during wartime. Britain, most of its allies, and many European neutrals soon followed suit. Russia and a few other countries waited until the next year and the United States adopted it in 1918.
Document 6: History of unmanned aerial vehicles: Later, in November 1917, the Automatic Airplane was flown for representatives of the US Army. This led the army to commission a project to build an ``aerial torpedo '', resulting in the Kettering Bug which first flew in 1918. While the Bug's revolutionary technology was successful, it was not in time to fight in the war, which ended before it could be fully developed and deployed.
Document 7: AAI RQ-2 Pioneer: The AAI RQ-2 Pioneer is an unmanned aerial vehicle (UAV) that had been utilized by the United States Navy, Marine Corps, and Army, and deployed at sea and on land from 1986 until 2007. Initially tested aboard USS "Iowa", the RQ-2 Pioneer was placed aboard s to provide gunnery spotting, its mission evolving into reconnaissance and surveillance, primarily for amphibious forces.
Document 8: Daylight saving time: George Hudson proposed the idea of daylight saving in 1895. The German Empire and Austria - Hungary organized the first nationwide implementation, starting on April 30, 1916. Many countries have used it at various times since then, particularly since the energy crisis of the 1970s.
Document 9: Lockheed MQM-105 Aquila: The Lockheed MQM-105 Aquila (Eagle) was the first small battlefield drone developed in the United States during the 1970s to act as a target designator for the US Army.
Document 10: Aerosport Inc: Aerosport Inc was a company founded by Harold Woods in Holly Springs, North Carolina in 1971 to market aircraft and plans for homebuilding.
Document 11: Daylight saving time: New Zealander George Hudson proposed the modern idea of daylight saving in 1895. Germany and Austria-Hungary organized the first nationwide implementation, starting on 30 April 1916. Many countries have used it at various times since then, particularly since the energy crisis of the 1970s.
Document 12: SunExpress: The airline was established in October 1989 and started operations in April 1990 with a charter service between Antalya and Frankfurt. SunExpress was founded as a joint venture between Turkish Airlines and the Lufthansa Group/Condor Flugdienst. In 1995, the Lufthansa Group transferred its SunExpress shares to Condor. All tourist flights operate under a single unit. In February 2007, all Condor shares were retaken by the Lufthansa Group as Condor was acquired by Thomas Cook AG (now Thomas Cook Group).
Document 13: Daylight saving time: Starting on April 30, 1916, the German Empire and its World War I ally Austria - Hungary were the first to use DST (German: Sommerzeit) as a way to conserve coal during wartime. Britain, most of its allies, and many European neutrals soon followed suit. Russia and a few other countries waited until the next year, and the United States adopted it in 1918.
Document 14: Airline: DELAG, Deutsche Luftschiffahrts - Aktiengesellschaft was the world's first airline. It was founded on November 16, 1909, with government assistance, and operated airships manufactured by The Zeppelin Corporation. Its headquarters were in Frankfurt. The first fixed wing scheduled air service was started on January 1, 1914, from St. Petersburg, Florida, to Tampa, Florida. The four oldest non-dirigible airlines that still exist are Netherlands' KLM (1919), Colombia's Avianca (1919), Australia's Qantas (1921), and the Czech Republic's Czech Airlines (1923).
Document 15: Santa Monica, California: Donald Wills Douglas, Sr. built a plant in 1922 at Clover Field (Santa Monica Airport) for the Douglas Aircraft Company. In 1924, four Douglas-built planes took off from Clover Field to attempt the first aerial circumnavigation of the world. Two planes made it back, after having covered 27,553 miles (44,342 km) in 175 days, and were greeted on their return September 23, 1924, by a crowd of 200,000 (generously estimated). The Douglas Company (later McDonnell Douglas) kept facilities in the city until the 1960s.
ground_truth: 1918
sub_queries: Air Express >> manufacturer Answer: Lockheed
Lockheed MQM-105 Aquila >> country Answer: the United States
What year did the United States finally adopt Daylight Saving Time? Answer: 1918