Year
Nitrogen
2000
63.18
2001
61.04
2002
59.59
2003
64.98
2004
54.28
2005
54.82
2006
57.38
2007
57.98
2008
52.87
2009
47.21
2010
50.65
2011
50.86
2012
52.01
2013
51.4
2014
48.4
2015
52.43