On 10 April 2018, we provided updated processed data files with the ethane 
column removed.  The ethane value was used only to provide a small correction
 to the methane isotopic ratio and was not of high enough quality to be used 
otherwise.  Inclusion of this data column was confusing to the user. We also 
added data from January - February 2017 to the dataset. Furthermore, we 
updated the readme, use constraints, and abstract files for consistency and 
changed the title to exclude the time frame. We updated the headers in order 
to improve clarity.