Question: The Gell-Mann–Nishijima formula was proposed by an American physicist who received a Nobel Prize in what year?

Context paragraphs:
Gell-Mann–Nishijima formula: The Gell-Mann–Nishijima formula (sometimes known as the NNG formula) relates the baryon number "B", the strangeness "S", the isospin "I" of quarks and hadrons to the electric charge "Q".  It was originally given by Kazuhiko Nishijima and Tadao Nakano in 1953, and led to the proposal of strangeness as a concept, which Nishijima originally called "eta-charge" after the eta meson.  Murray Gell-Mann proposed the formula independently in 1956.  The modern version of the formula relates all flavour quantum numbers (isospin up and down, strangeness, charm, bottomness, and topness) with the baryon number and the electric charge.

Nobel Prize in Physics: The Nobel Prize in Physics (Swedish: "Nobelpriset i fysik" ) is a yearly award given by the Royal Swedish Academy of Sciences for those who conferred the most outstanding contributions for mankind in the field of physics.  It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895 and awarded since 1901; the others being the Nobel Prize in Chemistry, Nobel Prize in Literature, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

Albert A. Michelson: Prof Albert Abraham Michelson (surname pronunciation anglicized as "Michael-son") FFRS HFRSE LLD (December 19, 1852 – May 9, 1931) was an American physicist known for his work on measuring the speed of light and especially for the Michelson–Morley experiment.  In 1907 he received the Nobel Prize in Physics, becoming the first American to win the Nobel Prize in a science.

Nobel Prize in Literature: Since 1901, the Nobel Prize in Literature (Swedish: "Nobelpriset i litteratur" ) has been awarded annually to an author from any country who has, in the words of the will of Alfred Nobel, produced "in the field of literature the most outstanding work in an ideal direction" (original Swedish: "den som inom litteraturen har producerat det mest framstående verket i en idealisk riktning").  Though individual works are sometimes cited as being particularly noteworthy, here "work" refers to an author's work as a whole.  The Swedish Academy decides who, if anyone, will receive the prize in any given year.  The academy announces the name of the chosen laureate in early October.  It is one of the five Nobel Prizes established by the will of Alfred Nobel in 1895; the others are the Nobel Prize in Chemistry, Nobel Prize in Physics, Nobel Peace Prize, and Nobel Prize in Physiology or Medicine.

Murray Gell-Mann: Murray Gell-Mann ( ; born September 15, 1929) is an American physicist who received the 1969 Nobel Prize in physics for his work on the theory of elementary particles.  He is the Robert Andrews Millikan Professor of Theoretical Physics Emeritus at the California Institute of Technology, a Distinguished Fellow and co-founder of the Santa Fe Institute, Professor in the Physics and Astronomy Department of the University of New Mexico, and the Presidential Professor of Physics and Medicine at the University of Southern California.

List of Nobel laureates in Physiology or Medicine: The Nobel Prize in Physiology or Medicine (Swedish: "Nobelpriset i fysiologi eller medicin" ) is awarded annually by the Swedish Karolinska Institute to scientists and doctors in the various fields of physiology or medicine.  It is one of the five Nobel Prizes established by the 1895 will of Alfred Nobel (who died in 1896), awarded for outstanding contributions in chemistry, physics, literature, peace, and physiology or medicine.  As dictated by Nobel's will, the award is administered by the Nobel Foundation and awarded by a committee that consists of five members and an executive secretary elected by the Karolinska Institute.  While commonly referred to as the Nobel Prize in Medicine, Nobel specifically stated that the prize be awarded for "physiology or medicine" in his will.  Because of this, the prize can be awarded in a broader range of fields.  The first Nobel Prize in Physiology or Medicine was awarded in 1901 to Emil Adolf von Behring, of Germany.  Each recipient receives a medal, a diploma and a monetary award that has varied throughout the years.  In 1901, von Behring received 150,782 SEK, which is equal to 7,731,004 SEK in December 2008.  In 2013, the prize was awarded to James E. Rothman, Randy W. Schekman and Thomas C. Südhof; they were recognised "after discovering how cells precisely transport material".  The award is presented in Stockholm at an annual ceremony on December 10, the anniversary of Nobel's death.

List of Danish Nobel laureates: This is a list of Danish Nobel laureates.  Since the Nobel Prize was established per the will of Swedish inventor Alfred Nobel in 1895, 12 of the prize winners have been from Denmark.  The first Danish Nobel laureate was Niels Ryberg Finsen, who won a Nobel Prize for medicine in 1903 for his work in using light therapy to treat diseases.  The most recent Danish Nobel Prize winner was Jens Skou who won the prize in chemistry for his discovery over the enzyme, Na+/K+-ATPase in 1997.  To date, of the 13 Nobel Prizes won by Danish people, 5 have been for medicine, 3 have been for physics, 3 have been for literature, 1 has been for chemistry and one has been for peace.

Eightfold Way (physics): In physics, the Eightfold Way is a theory organizing subatomic hadrons.  The name was coined by American physicist Murray Gell-Mann as an allusion to the Noble Eightfold Path of Buddhism.  It led to the development of the quark model.  An equivalent theory was independently proposed by Israeli physicist Yuval Ne'eman.

Clinton Davisson: Clinton Joseph Davisson (October 22, 1881 – February 1, 1958), was an American physicist who won the 1937 Nobel Prize in Physics for his discovery of electron diffraction in the famous Davisson-Germer experiment.  Davisson shared the Nobel Prize with George Paget Thomson, who independently discovered electron diffraction at about the same time as Davisson.

Ada Yonath: Ada E. Yonath (Hebrew: עדה יונת‎ ‎ , ] ) (born 22 June 1939) is an Israeli crystallographer best known for her pioneering work on the structure of the ribosome.  She is the current director of the Helen and Milton A. Kimmelman Center for Biomolecular Structure and Assembly of the Weizmann Institute of Science.  In 2009, she received the Nobel Prize in Chemistry along with Venkatraman Ramakrishnan and Thomas A. Steitz for her studies on the structure and function of the ribosome, becoming the first Israeli woman to win the Nobel Prize out of ten Israeli Nobel laureates, the first woman from the Middle East to win a Nobel prize in the sciences, and the first woman in 45 years to win the Nobel Prize for Chemistry.  However, she said herself that there was nothing special about a woman winning the Prize.

Supporting paragraphs: Gell-Mann–Nishijima formula Murray Gell-Mann
Answer: 1969