Here's why:
* Varying Levels of Proficiency: Some people may be native English speakers, while others may be fluent but not native. Some might have basic understanding, while others may struggle with the language.
* Data Collection Challenges: Surveys and censuses can't always accurately capture everyone's language abilities. Some people might not be counted, or they might not report their language use accurately.
* Language Diversity: The US is a very diverse country with many languages spoken. Even among people who report English as their primary language, there might be variations in dialect and accent.
However, we can look at some relevant statistics:
* 2020 Census: Reported that 93.4% of the US population aged 5 and over spoke English at home. This doesn't mean they are fluent, but rather that they use English as their primary language.
* US Department of Education: Estimates that about 9% of school-aged children speak a language other than English at home.
Therefore, while an exact number is not available, it's safe to say that the vast majority of the US population speaks English, with varying levels of proficiency.