National Trends in Carbon_Monoxide Concentrations in 2000 - 2010
Year Mean Number of Trend Sites 10th Percentile 90th Percentile
2000 3.51132075471698 265 1.5 5.6
2001 3.28264150943396 265 1.5 4.9
2002 2.94830188679245 265 1.4 4.7
2003 2.76830188679245 265 1.4 4.5
2004 2.5366037735849 265 1.2 3.9
2005 2.32471698113207 265 1.2 3.6
2006 2.22094339622641 265 1.1 3.4
2007 1.95339622641509 265 1 3.1
2008 1.82452830188679 265 0.9 2.9
2009 1.7388679245283 265 0.9 2.7
2010 1.62792452830188 265 0.8 2.5