I know clothes have changed sizes since the 50's, probably in the last few years they have more. In her day Meralyn Monroe wore a size 12, these days she would be a size 4-6. It depends alot on brands and also it seems what end of the scale things are on. I mean as in the lower priced discount stores seem to size things smaller, while more expencive stores seem to have a size 8 marked as 12.

If you ever want to be severly depressed, go look at wedding dresses. They lady helping me stated flat out you have to look at dresses at least 3 sizes bigger then what you would normally wear because they size them so differently.