Year | Concentration |
---|---|
2000 | 21.19 |
2001 | 21.01 |
2002 | 20.53 |
2003 | 20.86 |
2004 | 20.7 |
2005 | 20.77 |
2006 | 20.79 |
2007 | 21.24 |
2008 | 21.41 |
2009 | 21.1 |
2010 | 21.47 |
2011 | 20.63 |
2012 | 21.25 |
2013 | 21.14 |
2014 | 21.27 |
2015 | 21.31 |
2016 | 21.61 |
2017 | 21.05 |
2018 | 21.15 |
2019 | 20.78 |
2020 | 20.42 |
2021 | 20.51 |