SACRAMENTO—California's population has topped 38 million, according to a new report from the state Department of Finance.

The department's demographics unit estimates that California's population grew by nearly 436,000, or 1.16 percent, in the 12 months between July 1, 2007 and July 1, 2008, reaching 38.1 million.

That's an increase of nearly 4.3 million residents since the last national census in 2000.

Los Angeles remains the state's most populous county with more than 10 million residents, but Placer County east of Sacramento had the biggest percentage increase in population in the 12-month period. It grew by 2.6 percent.

Nineteen other counties also had higher growth rates than the state as a whole: Imperial, Riverside, Tulare, Kern, Sutter, Madera, Santa Clara, Yuba, Fresno, San Francisco, Merced, San Diego, Yolo, Kings, Contra Costa, San Mateo, Alameda, Napa and San Joaquin all grew by more than 1.16 percent.

Twenty-seven counties had lower rates of growth and 11 of them—Mariposa, Nevada, Mono, Trinity, Sierra, Alpine, Tuolumne, Inyo, Plumas, Amador and Lassen—actually lost population during the 12-month period, the report said.