Why is "Number of Returns Filed" included on each table?
To give context. If 40% of all qualified dividends income is going to those making >1M a year then it's relevant to know that those making >1M a year account for 0.3% of taxpayers.
Why does it look like some bars are missing on a few data sets?
On a few of the categories the number of filers is so small for a specific income category that the IRS omits this data to protect privacy (i.e. the number of filers with income from farming and an AGI >1M is very few.)