A bunch of things got me wondering about child care costs. How unaffordable are they for low-income parents who don’t have the benefit of subsidies? The annual survey reports by the National Association of Child Care Resource and Referral Agencies are the best source of data on affordability I’ve found. So I pulled figures from the latest report — most of them for 2009. Then did some calculations of my own — or more precisely, told Excel to do them. Here’s a summary of key results, plus some Google gleanings about impacts.