Here is the chart (from page 65 of the report). Notice not only the increase in number of special deductions, exclusions and credits (about 90 in 1980 versus 250 in 2010), but also the tremendous increase just from 2006 to 2010.
This is a lot of special rules that are not crucial to defining the income tax base. These expenditures do not include the standard deduction and personal exemption as they are viewed as part of a basic income tax (to recognize that some income should be untaxed as you need it to live on). Special rules, especially so many of them, cause the following problems:
- Economic inefficiencies (non-neutral system)
- Lack of transparency as to what one's real tax rate is
- Higher tax rates
btw - Another interesting item in the report is the listing of how capital gains have been taxed since 1921 when any special treatment for them was added to the Code (pages 57 - 62).