Data for greenhouse gas (GHG) are coming from
United Nations Framework Convention on 
Climate Change website:

http://unfccc.int/ghg_data/ghg_data_unfccc/time_series_annex_i/items/3814.php

"""
The UNFCCC Website is the property of the secretariat of the United Nations 
Framework Convention on Climate Change. The UNFCCC logo  may be downloaded 
to view the website and print out information. However, if you should require 
the logo for other purposes, you will need the written authorization of the 
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Photos provided on the UNFCCC flickr account may be downloaded and used free 
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All official texts, data and documents are in the public domain and may be 
freely downloaded, copied and printed provided no change to the content is 
introduced, and the source is acknowledged.
"""