This pervasive weakness in global business investment growth is also a challenge to understand, but the most compelling explanations are the combination of heightened uncertainty, especially about the profile for demand growth, which has been compounded by political events, and elevated risk aversion on the part of firms coming out of the Great Recession.13 Chart 13: Since the Great Recession, world trade has flattened relative to GDP Nominal goods imports and exports as a share of GDP, annual, 2000–15 % 80 70 60 50 40 30 2000 2001 2002 2003 2004 2005 2006 2007 2008 2009 2010 2011 2012 2013 2014 2015 Canada Sources: International Monetary Fund, Haver Analytics and Bank of Canada calculations  World Last observation: 2015  The second explanation for the recent weakness in global trade growth is that the pace of trade liberalization has recently slowed, if not reversed.
Clearly, China can join the WTO only once, as it did in 2001. However, since the crisis, the WTO has recorded a troubling increase in the number of protectionist measures.14 For Canadian exports, the most noteworthy concern being expressed by firms we survey is about the US “Buy American” policies.