Year 0-6,000 μg/m3·h 6,000-12,000 μg/m3·h 12,000-18,000 μg/m3·h Greater than 18,000 μg/m3·h
1996 6.2 21.7 24.8 47.2
1997 6.6 27.8 32.6 33
1998 9.7 16 29.1 45.1
1999 2.4 13.2 42.7 41.7
2000 10.7 25.4 21.2 42.6
2001 8.2 20.7 22 49.1
2002 4.2 25.1 23.6 47.1
2003 5.7 10.5 13.2 70.5
2004 15 24.6 23.2 37.3
2005 7.7 16 26.8 49.5
2006 1.9 4.9 20.3 73
2007 17.8 26.9 19.9 35.5
2008 4.3 23.3 33.5 38.8
2009 15 34.5 25.7 24.7
2010 9.9 29.6 37.2 23.3
2011 6.5 28.5 45.4 19.5
2012 8.2 34.6 28.2 29.1
2013 14.7 38.6 24.5 22.2
2014 9.2 38.5 33 19.3
2015 15.6 26.6 25.4 32.4
2016 18.9 34.3 26.3 20.5
2017 19.5 32.7 20 27.8
2018 4 16.8 31.1 48.2
2019 9.3 25 26.4 39.3
2020 23.3 48.3 23 5.5