I dunno man, disfluencies like "um" are an integral part of language. I'd put my money on them being plenty common in everyday language 45 years ago.

http://en.wikipedia.org/wiki/Speech_disfluency

No, I totally agree with you, but there was a very specific period a handful of years ago I noticed people seemed compelled to fill any dead air whatsoever between thoughts with literally strings of "um"'s... So much so they'd still be saying an "um" after they were ready to say the next word (you could tell by their face and speech)

People have always used fillers (aka filled pauses) in speech. There is no evidence to suggest they have become any more or any less common.

For example, http://separatedbyacommonlanguage.blogspot.com/2008/05/uh-er... cites a play by Agatha Christie (who dies in 1976) which is full of um's (using the British spelling of erm).