Year	Lower than 10 mg/m³.h	10-20 mg/m³.h	20-30 mg/m³.h	30-50 mg/m³.h	Greater than 50 mg/m³.h
2004	2.0	49.3	20.1	21.3	7.2
2005	24.7	18.0	18.9	28.7	9.7
2006	0.2	31.8	18.0	39.8	10.2
2007	40.3	14.6	13.6	24.5	6.9
2008	21.7	31.2	21.5	25.1	0.5
2009	34.7	19.3	18.4	24.2	3.3
2010	38.9	15.1	25.1	19.0	2.0
2011	32.9	16.3	25.8	21.9	3.0
2012	36.7	18.7	18.2	22.9	3.6
2013	34.4	24.2	19.3	18.3	3.7
2014	33.4	31.7	25.1	9.8	0.1
2015	42.2	7.7	17.2	28.8	4.1
2016	39.1	19.2	24.1	16.6	1.0
2017	43.6	16.8	18.3	18.4	3.0
2018	13.0	30.2	16.1	35.9	4.8
2019	15.6	32.2	20.9	29.0	2.4