Our analysis of U.S. Census data shows that Chinese is the third-most spoken language in 15 of the city's 55 districts. According to the Asian American Foundation, the city's Chinese cohort grew by 7.6% between 2015 and 2020, despite an overall population.
Imma guess the unfinished sentence was supposed to end in "decline."
ETA: Kinda amusing that the language isn't specified as "Mandarin," but I guess it's a reasonable assumption as my understanding is Cantonese use is significantly diminished despite being a somewhat more expressive variant (again, this is what I've read - I've no personal knowledge of either).