  
<prompt> De jure mean household size for the survey years 1990, 1997, 2002, 2007, 2009, and 2012, with 95% confidence intervals
  
 [[1990, 6.9], [1997, 6], [2002, 5.7], [2007, 5.3], [2009, 5.1], [2012, 5.1]] 
 <response> Figure 2 shows that the mean de jure (or usual resident) household size significantly decreased from 6.9 in 1990 to 5.1 in 2009, but remained unchanged between 2009 and 2012  