National Trends in Sulfur_Dioxide Concentrations in 2000 - 2012
Year Mean Number of Trend Sites 10th Percentile 90th Percentile
2000 74.0811538461538 260 12.8 161.5
2001 73.7678205128205 260 13.65 154
2002 66.789423076923 260 12.3 136
2003 68.2125 260 13 149
2004 65.1841666666666 260 12 136.166666666666
2005 65.493141025641 260 11 136.5
2006 61.9351282051282 260 11.5 136.5
2007 58.6643589743589 260 10.25 134.5
2008 53.2108974358974 260 9.75 127.5
2009 45.608782051282 260 8.2 111
2010 41.6548076923076 260 7 93
2011 34.9830128205128 260 7 78.5
2012 33.8230769230769 260 5.4 77.95