Year	mg P / l
2000	0.41
2001	0.4
2002	0.4
2003	0.39
2004	0.41
2005	0.39
2006	0.41
2007	0.37
2008	0.33
2009	0.32
2010	0.34
2011	0.35
2012	0.4
2013	0.4
2014	0.39
2015	0.44
2016	0.52
2017	0.53