The differences follow:
2005 - 2005 = 0
2006 - 2005 = 1
2007 - 2005 = 2
2007 - 2006 = 1
...etc. I'll leave it to the reader to provide a proof.
2005 - 2005 = 0
2006 - 2005 = 1
2007 - 2005 = 2
2007 - 2006 = 1
...etc. I'll leave it to the reader to provide a proof.