The growth in the divide is caused by changes in CEO compensation that reward CEOs of public companies with large stock option rewards. In theory this is a reform-- only CEOs with rising stocks should get paid. Also just looking at the top public companies isn't really representative of the economy as a whole. The median CEO really makes around $360,000, which is a respectable 9-1 ratio.
Further, being paid $9.6mil/year as a CEO is exceptionally rare. $10.2mil of total compensation would have placed you in the top 100 out of the 100Ks (millions?) of CEOs world wide in 2012. $20mil would have placed you in the top 20.
http://chiefexecutive.net/how-much-does-the-average-ceo-real...