[MMM]

Originally Posted by RickOShay

I am mostly speaking in terms of modern language and the frequency in which loanwords (a lot of which come from English) are used.

Even so, the simple fact that a katakana dictionary can have more than 48,000 entries, tells me that the frequency of katakana being used even in everyday language must be way above 2%.
Just pay close attention next time you read something, or even talk to somebody. I mean I know it all still depends, but it's a lot.

Amazon.co.jp： コンサイスカタカナ&#x 8A9E;辞典: 三省堂編修所: 本

Depends on what industry you are in...but I cannot think of any industry where one out of five words in any sentence would be in katakana. Please feel free to correct me on that.

Yes, there are many katakana words in Japanese, but not 20% or 10% in any average conversation.

Regardless, this is not what the OP is talking about.