Color of Diff Oil. I replaced my differential fluid at 60k miles, I'm now at 71k and today when getting my oil changed the guy showed me the oil and it was dark brown in the rear while the front was still the clearish-yellow like it was when I put them in.
The average tax rate is the tax rate you pay when you add all sources of taxable income and divide that number into the amount of taxes you owe. In other words, you can calculate your average tax rate by dividing your total tax obligation by your total taxable income.
According to the IRS's preliminary data from the 2015 tax year (the returns you filed during 2016), there was a total of $1.454 trillion in income tax owed, which translates to an average effective federal income tax rate of about 13.5% per return. However, that doesn't tell the entire story, as there are several other taxes most Americans pay.