Year
|
0 – 6000 (μg/m³).h
|
6000 – 12000 (μg/m³).h
|
12000 – 18000 (μg/m³).h
|
Greater than 18000 (μg/m³).h
|
1996
|
7.63
|
25.61
|
23.11
|
43.65
|
1997
|
9.78
|
29.65
|
30.69
|
29.88
|
1998
|
15.24
|
16.01
|
27.46
|
41.28
|
1999
|
4.47
|
17.14
|
40.26
|
38.13
|
2000
|
16.14
|
24.93
|
20.0
|
38.93
|
2001
|
10.61
|
23.57
|
20.73
|
45.09
|
2002
|
10.63
|
24.04
|
22.2
|
43.13
|
2003
|
8.54
|
13.63
|
12.64
|
65.19
|
2004
|
20.39
|
23.88
|
21.43
|
34.29
|
2005
|
12.73
|
16.61
|
25.24
|
45.42
|
2006
|
2.43
|
7.17
|
21.66
|
68.74
|
2007
|
23.68
|
25.32
|
18.77
|
32.23
|
2008
|
4.72
|
28.27
|
31.58
|
35.44
|
2009
|
20.05
|
33.6
|
24.06
|
22.3
|
2010
|
15.39
|
28.83
|
34.58
|
21.2
|
2011
|
12.77
|
27.07
|
42.51
|
17.66
|