Why is this and why was 2002-7 period the exception?
Quite simply because, despite a 40m population (60% barely plugged into the economy), we still eat, walk and sleep politics. In Kenya, good politics=good economy and not vice versa as you'd find in most developed countries. In 2007, Kenyans thought it'd be a walkover for Raila and as such everybody kept their money in the NSE or were too pre-occupied with the NSE bullrun.
Given PEV at the start of this 2008-12 political term and consequent political; the ongoing rain short-fall; the out of his depth CBK governor; relatively high oil prices, cycle will be followed to the t.