The graph does show a decline in wealth in 2008 and 2009 for which one might, without committing anachronism, blame GWB. That would likely be due to the housing bubble bursting. That said, housing prices probably largely recovered by 2010 or 2011 (I'm going by Silicon Valley, which may be atypical), so why did the decline in wealth continue decline after 2010? That's a question DU-folk should be ducking, not bringing up. Though, as zg suggested, DU-folk probably aren't very good with Math or chronology.
Fixed a typo.