However, we can look at some data points to get a general idea:
* The US Census Bureau doesn't track language proficiency in detail, focusing on language spoken at home. This data is likely to include people who have some basic understanding of Mandarin, but not necessarily fluency.
* The Modern Language Association (MLA) reports that Mandarin is the 4th most commonly studied foreign language in US colleges and universities. This indicates a significant number of students are learning Mandarin, but it doesn't translate directly to the general population.
* Anecdotally, Mandarin is becoming increasingly popular in the US, especially in areas with large Chinese communities. This suggests a growing number of Americans are learning Mandarin for personal or professional reasons.
In summary, while we can't give a definitive percentage, it's safe to say that Mandarin proficiency in the US is growing, but it still remains a relatively uncommon language compared to others like Spanish or French.