"During The Somme, the British bombardment consisted of 1,537 guns firing over 1,500,000 shells over a period of 168 hours averaging 8,929 shells fired per minute."
That is just... staggering. I can't find a source for it, but I remember some factoid stating that on average it took several hundred shells to kill one soldier. That's not to say they had to take several hundred hits, but that on average that's how many shells it took to rack up one kill.
(from: http://www.tommy1418.com/wwi-facts--figures--myths.html)
*Edit for caps only