They are all used just as much as each other! 'A moment of Silence' is probably used in that moment, like in a ceremony. Like it would be said as an instruction 'a moment of silence' and then everyone would do it. Whereas, 'a minute silence' would be in the sentence: 'let's join for a minutes silence'.

a minute of silence would be for mourning and a moment of since would be for a pause to reflect, i'd say?

I take no credit - it's a handy tool from google :) But I'm glad you like it.

U are awesome, Michael. I used to do the "exact match" search simply on Google.com, now I've learned something so cool from u: books.google.com. So I have a chart showing me the tendency of words with more details. Thank you so much!

OMG, I had no idea I could do that. How useful! Thank you so much, Michael.