The following sources may be useful for collecting data about countries’ economic development and economic situation:
http://www.economist.com/blogs/graphicdetail/2014/03/european-economy-guide
http://www.oecd-ilibrary.org/economics/oecd-factbook-2013_factbook-2013-en
http://www.oecd.org/statistics/datalab/
http://www.weforum.org/reports
http://www.oecd-ilibrary.org/economics/country-statistical-profiles-key-tables-from-oecd_20752288