I can't remember if it has always been 3 tiers but I thought it was 4 tiers at one point.
$0-75k = 12%
$75K - 225 = 25%
$225+ = 33%
Standard deduction = $12k/yr
http://www.foxbusiness.com/politics/2017/01/23/trump-doubles-down-on-promise-to-give-americans-tax-break.html