Year	<6,000 μg/m³·h	6,000-12,000 μg/m³·h	12,000-18,000 μg/m³·h	>18,000 μg/m³·h
2000	10.87	25.77	21.5	41.87
2001	8.3	20.95	22.26	48.49
2002	4.27	25.47	23.88	46.38
2003	5.82	10.66	13.41	70.11
2004	15.15	24.92	23.05	36.88
2005	7.76	16.25	27.14	48.85
2006	1.9	4.88	20.27	72.96
2007	17.02	27.08	20.11	35.79
2008	4.07	23.12	33.84	38.98
2009	14.35	35.06	25.56	25.04
2010	9.19	30.06	37.73	23.02
2011	5.73	28.89	45.73	19.65
2012	7.42	34.99	28.13	29.45
2013	13.97	39.17	24.55	22.31
2014	8.54	38.94	32.95	19.58
2015	14.91	27.03	25.8	32.27
2016	21.32	37.86	24.87	15.96
2017	22.03	37.4	17.05	23.52
2018	4.22	18.89	33.83	43.06
2019	10.11	28.45	29.34	32.1
2020	26.15	53.58	16.87	3.4