"remained persistently" is correct and usable in written English.
You can use it to show that a person, feeling, attitude, or situation has not changed over a long period of time. Example sentence: Despite their differences, their love for each other remained persistently strong.
But they remained persistently silent, even among themselves.
In addition, inflation has remained persistently below the Fed's 2% target rate.
These students had remained persistently poor readers, scoring poorly on speed as well as comprehension.
Moreover, Germany's electricity prices have remained persistently high even at times when they would have been expected to fall.
Similarly, the yen remained persistently strong in the international currency markets, hovering at about 76.60 yen per United States dollar.
During the 1980s and 1990s, Cleveland had embarked on a program of revitalization, but the inner neighborhoods remained persistently black and poor.
For many protesters, the message has remained persistently local, particularly when compared with the sprawling ambitions of the gatherings in Manhattan and other cities.
The Frankfurt-based European bank has reduced its rates only once this year, reflecting its concern that inflation in the euro zone has remained persistently above its annual target of 2percentt for more than a year.
And in this business cycle the three main vehicles through which lower rates affect business, investor and consumer behavior -- the stock, bond and currency markets -- have remained persistently unresponsive to the Fed's actions.
Although a Chinese slowdown has hit profits and an investment in American shale, where natural gas prices have remained persistently low, looks misjudged, BHP is in much better shape than its two rivals.
HONG KONG — China stepped up its campaign to combat rising inflation and restrain the sizzling pace of economic growth Tuesday by further restricting lending at the nation's banks after government data showed inflation remained persistently high in May.
