'fell in popularity' is grammatically correct and can be used in written English.
For example: Over the years, the band's music fell in popularity as their sound became outdated.
The churn of what's rising or falling in popularity is accelerated in smartphone apps.
As hard drugs fall in popularity, clinical services may simply pull in more cannabis users.
Charlotte may have fallen in popularity over the last decade – according to the Office for National Statistics it was ranked 21st in 2013 – but some colourful royals have borne the name.
You described the Scottish National Party's government as falling in popularity and you provided Ipsos MORI and YouGov polls that rated their support at 34% and 35% respectively.
QUESTION FROM RICHARD : Seeing that we are in a digital age, have you seen cartoons fall in popularity... ROBERT MANKOFF: Not at all.
The subjects which experienced the biggest year-on-year falls in popularity, in percentage terms, were Critical Thinking, General Studies and PE, which declined by 12.7% to just under 17,000 candidates.
After all the boosts and dips, the overall effect has been that Trump has fallen in popularity while Clinton has risen.
New figures from Hitwise, which researches web traffic, have shown that travel sites are falling in popularity, with BA falling from 11th position to 43rd and budget airlines such as Ryanair and Easyjet also slipping down the rankings.
Key measures, including satisfaction with democracy, trust in government and loyalty to major parties, are at record lows among Australian voters while party leaders are suffering sustained falls in popularity unlike any other period in recent history.
The council leader, Ranjit Banwait, said the local authority was going through "the worst cuts in history" and the additional money could be used to improve local parks that had fallen in popularity.
