Tucson General Hospital sometimes has to treat people bitten by rattlesnakes. In the past 15 years they have observed the following numbers of rattlesnake-bite cases: Year Number of Cases
2001 4
2002 8
2003 9
2004 2
2005 3
2006 4
2007 12
2008 8
2009 4
2010 3
2011 5
2012 10
2013 11
2014 6
2015 7

At the beginning of each year, the hospital has the opportunity to pre-order anti-venom kits at cost of $350 each. Treating each snake-bite case requires one anti-venom kit. The kits expire after one year, after which any unused kits must be disposed of at a cost of $10 each. If the hospital runs out of pre- ordered anti-venom kits before the end of the year, it may immediately obtain a functionally equivalent packet of medications from a local pharmacy, but the cost is $500 per case treated.

Required:
Assuming the past data presented above are representative of the number of snake-bite cases that may be expected in the future, how many anti-venom kits should the hospital pre-order each year?