Haha, my wife and I are having the same conversation right now. It's insane that this kind of conversation even exists in the first place! Looking at a visual that I found on NYTimes (http://www.nytimes.com/interactive/2015/04/16/upshot/marriag...), it seems like at the high end it kicks in at ~180k, but it seems to also exists at the very low end as well ~35k.