Average word use: the phrase has little utility because it cannot be define as it would pertain to many individuals.

"Richard Lederer, a lion among linguistics, tells us that English is the most cheerfully democratic language in the history of mankind. It has 616,500 entries in the Oxford English Dictionary. This compares with a vocabulary of about 185,000 words for German, 130,000 for Russian, and 100,000 for French. Yet the average English speaker possesses a vocabulary of 10,000 to 20,000 words, Lederer observes, but actually uses only a fraction of that, the rest being recognition or recall vocabulary."

IMO, as is the phrase IMO, it's a matter of opinion, level of 'education', etc. In some ways I see it as being about as pertinent as IQ to measure 'smarts'.