For example, wheat, rice, and cooking oil - products that are imported on the African continent - exhibit lower price volatility than the prices of domestically produced staples. Efforts to increase the tradability of these less traded commodities even regionally would help to lower their high domestic price volatility. Specific data on policy changes may be the most informative. In a study of 14 developing countries, Balzer (2013) notes that in 2007-08 export restrictions were applied to food staples by eight (China, Egypt, Ethiopia, India, Kenya, Malawi, Viet Nam and Zambia); import tariffs on one or more staples were waived by five (Bangladesh, Egypt, Kenya, Nigeria and Senegal).