I was going to write just the 50's, but decided for the century prefix of 19 as well.  And I realized that, God-willing, in my lifetime it will be necessary to make century distinctions more and more frequently, which is something that people who span two centuries (not in physical age, duh, but in their lifetime) have to think about.  It's kind of weird, and another pleasant reminder of the fact that I'm growing older.

Which, if nothing else, beats the alternative.