California’s 2018 population growth was the slowest in state history, new demographic data show underscoring shifting immigration patterns, declining birthrates and economic strains that are making it harder for some to afford living here. The state added 186,807 residents last year, bringing the estimated total population to 39,927,315 as of Jan. 1, according to estimates released by the state Department of Finance on Wednesday. The overall growth rate slipped to 0.47% last year from 0.78% in 2017, the slowest since data collection started in 1900, department spokesman H.D. Palmer said.