ANNAPOLIS, NOV. 5 -- The number of reported crimes in Anne Arundel County was 5 percent lower in the last nine months than it was during the same period last year, suggesting that figures for the year could reverse a sharp increase last year, police said yesterday.

County police marked the occasion by staging one of their largest-ever drug raids this morning, rounding up 64 suspected drug dealers and users.

Police officials said they believed the arrests would break up about a dozen small to medium drug rings in the county, most of which dealt in cocaine. The arrests, scattered throughout the county, followed a nine-month investigation.

Police Chief George Wellham III said adult arrests were up 47.3 percent, from 4,740 during the first nine months last year to 6,984 for the same period this year.

But reports of violent crime were down 5.6 percent -- from 734 to 693 -- while the number of reported crimes against property fell by 5 percent, from 10,816 cases to 10,280.

The number of crimes reported annually had dropped steadily since 1981 before it jumped a record 20 percent last year, police said.

Wellham said he believed there was "a definite correlation" between increased arrests and a falling crime rate, meaning that the more criminals are locked up the fewer crimes can be committed.

He also credited the assignment of narcotics detectives to district stations, increased numbers of police officers -- 34 officers have been added since January -- and cooperation with the City of Annapolis.

However, County Executive O. James Lighthizer said it was impossible to attribute definitely the falling crime rate to new police work, or to promise that it will not reverse.

"Crime statistics are a little like the stock market," he said. "Who knows? We think there's a correlation. It's certainly good news, in the sense that something positive is happening."