Seems to me that Rob overlooked the single biggest change aside from the decline in interest rates.  Which is the shift from the number of taxpayers with DB pension plans to taxpayers with DC pension plans and/or reliance on their own savings.  In other words since the 80s the number of taxpayers who won't have a DB pension to fund their retirement has grown significantly.  Meaning that funds have shifted from pension funds to individual taxpayer investment accounts.  Odds are though that the pension funds also held a large proportion of dividend paying stocks.