Passage: Joining Einstein, Bertrand Russell and eight other leading scientists and intellectuals, he signed the Russell-Einstein Manifesto issued July 9, 1955. He also supported the Mainau Declaration  of July 15, 1955, signed by 52 Nobel Prize laureates.In May 1957, working with  Washington University in St. Louis professor Barry Commoner, Pauling began to circulate a petition among scientists to stop nuclear testing.  On January 15, 1958, Pauling and his wife presented a petition to United Nations Secretary General Dag Hammarskjöld calling for an end to the testing of nuclear weapons.  It was signed by 11,021 scientists representing fifty countries.In February 1958, Pauling participated in a publicly televised debate with the atomic physicist Edward Teller about the actual probability of fallout causing mutations.  Later in 1958, Pauling published No more war!, in which he not only called for an end to the testing of nuclear weapons but also an end to war itself . He proposed that a World Peace Research Organization be set up as part of the United Nations to "attack the problem of preserving the peace".Pauling also supported the work of the St. Louis Citizen's Committee for Nuclear Information (CNI). This group, headed by Barry Commoner, Eric Reiss,  M. W. Friedlander and John Fowler, organized a longitudinal study to measure radioactive strontium-90 in the baby teeth of children across North America.  The "Baby Tooth Survey," published by Dr. Louise Reiss, demonstrated conclusively in 1961 that above-ground nuclear testing posed significant public health risks in the form of radioactive fallout spread primarily via milk from cows that had ingested contaminated grass.  The Committee for Nuclear Information is frequently credited for its significant contribution to supporting the test ban, as is the ground-breaking research conducted by Dr. Reiss and the "Baby Tooth Survey".Public pressure and the frightening results of the CNI research subsequently led to a moratorium on above-ground nuclear weapons testing,...

Question: What year was a calling for the end of nuclear weapons petitioned to the UN Secretary?
1958