National Trends in PM10 Concentrations in 1990 - 2008

Year	Mean	Number of Trend Sites	10th Percentile	90th Percentile
1990	80.7692307692307	325	43	127
1991	79.5107692307692	325	43	132
1992	71.3579487179487	325	41	113
1993	70.6579487179487	325	42	108
1994	68.1379487179487	325	39	106
1995	67.7184615384615	325	38	107
1996	62.1261538461538	325	36	99
1997	61.9784615384615	325	36	98
1998	60.2025641025641	325	38	92
1999	65.1733333333333	325	38	106
2000	62.6010256410256	325	36	101
2001	61.6553846153846	325	36	95
2002	61.816923076923	325	37	95
2003	62.3553846153846	325	33	109
2004	53.6338461538461	325	31	82
2005	57.1938461538461	325	34	87
2006	56.3876923076923	325	34	88
2007	58.36	325	35	89
2008	55.9292307692307	325	33	88