How often do stock market crashes happen versus market gains?

They seem to either be predictable or the terms bull market bear market, crash versus correction, it all gets so technical yet *supposedly* online articles or encyclopaedias will say "oh well markets every so many point years have gains and losses or dips and rises and blah blah" and etc jargon. I mean does any average Joe actually understand it all or any average Jane lol
How often do stock market crashes happen versus market gains?
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