I would go so far as to say the majority of people I know say like. Even this insanely smart 24- year old guy who I worked with and was in graduate school for psychology. He recorded an interview and was telling me how he noticed that he said like more than he should. So, like, yeah.

Yep, it's the crutch words for ya, and y'know is mine.

But, I do notice I don't use it as much when I'm speaking to a stranger or when speaking something rehearsed.

Me neither. In interview situations, the fact that I'm already speaking slower and thinking about what I'm saying actually ends up in my not using like all the time. I guess that's handy.