Figure 16	
"Trends in the Occurrence of MTBE in Drinking Water Derived from Ground Water in 6 Northeast States, 1993-2006"	

Title:	"Detection frequency of MTBE in drinking water derived from ground water and median content of MTBE in gasoline in six Northeast States, 1993-2006."
	
	
Description:	This is a graph of MTBE detection frequencies and median MTBE content in gasoline for all States by year.
	
	
	
Origin of data:	The data were obtained from the full data set on MTBE in drinking water and the data on MTBE in gasoline: frozen_data_set_for_both_original_and_new_reports.rdb
	
	
	
Manipulation of data set:	"Initially, data was made unique by PWSID and SampleYear retaining any quantified concentrations of MTBE.  Then, detection frequencies of MTBE in drinking water for all systems in all States by year were computed from the full MTBE in drinking water data set and median contents of MTBE in gasoline for all States by year were computed from the MTBE in gasoline data set (NIPER data)."
	
	
	
Other:	The data on MTBE content in gasoline was obtained from the NIPER survey.  Data are located here:  NIPER_data_set_PROPRIETARY_NOT_FOR_PUBLIC_RELEASE.rdb
	
	
