* Context: The most common words in a scientific paper are likely different from the most common words in a casual conversation.
* Frequency: Even within a specific context, some words are used much more frequently than others. It's difficult to decide where to draw the line for what constitutes a "most used" word.
* Vocabulary Size: The average person's vocabulary is far smaller than the total number of words in the English language. So, even if we could identify the "most used" words, that wouldn't necessarily reflect the words a typical person uses.
However, some general information can be given:
* Zipf's Law: This law states that the frequency of a word is inversely proportional to its rank in a frequency list. So, the most frequent word is used twice as often as the second most frequent word, three times as often as the third most frequent, and so on. This implies that a small number of words are used very frequently.
* Studies: Studies have shown that a surprisingly small percentage of words accounts for a large portion of written and spoken language. For example, the top 1,000 words in English are thought to account for about 85% of written text.
In conclusion: While a precise percentage is impossible to determine, it's safe to say that a relatively small percentage of English words are used most frequently, and those words make up a large portion of the language we encounter.