Table:
text: List of rampage killers
Workplace killings
Workplace killings
Perpetrator Date_ Year_ Location_ Country Killed Injured
Sanurip , 36 04.15 April 15 1996 Timika Airport Indonesia 16 11
Chelakh, Vladislav , 19 05.27 May 27/28 2012 Arkankergen frontier post Kazakhstan 15 0
Sherrill, Patrick Henry , 44 08.20 Aug. 20 1986 Edmond , OK U.S. 14 06 6
Hasan, Nidal Malik , 39 11.05 Nov. 5 2009 Fort Hood , TX U.S. 13 32
Barton, Mark Orrin , 44 07.27 July 27–29 1999 Atlanta , GA U.S. 12 13
Alexis, Aaron , 34 09.16 Sep. 16 2013 Washington, D.C. U.S. 12 3
Lz 04.32 1979.9 Fz Tx 4.9 0.9

text: List of rampage killers
Workplace killings
Workplace killings
Perpetrator Date_ Year_ Location_ Country Killed Injured
Leung Ying , 29 08.22 Aug. 22 1928 Fairfield , CA U.S. 11 04 4
Tazmal Hossein 12.01 Dec. 1 1914 Naihati India 10 11
Kim Won-jo, 25 05.01 May 1 1974 Kimpo South Korea 10 03 3
Vaganov, Artur , 22 06.01 June 1 1997 Sida Abkhazia 10 03 3
Sz 07.32 1989.9 Lz Lz 5.9 02.9
Lee Wei, 41 04.05 April 5 1962 Patch Taiwan 10 0.2 0-2+
Ahmed Gul, 46 04.27 April 27 2011 Kabul Afghanistan 9 01.6 1–6
Smith, William Vincent, 19 04.23 April 23 1946 LST 172 U.S. 9 01 1
Unknown 07.29 July 29 1982 Maputo Mozambique 9 0.0 ?
Moreño, Jonathan, 31 01.16 Jan. 16 2005 Kalibo Philippines 8 29–33

Question: What is the average year when the country is "USA" and the location is "Edmond, OK" for the list of workplace homicides by gunman?