SACRAMENTO – California's adult smoking rate has fallen to a historic low as young adults – the first generation to grow up with the state's aggressive anti-tobacco campaign – posted their biggest decline in nearly a decade, health officials reported yesterday. Only 15.4 percent of California adults still smoke, according to a survey of 8,000 people conducted throughout 2004. That figure, down from 16.2 percent the year before, represents nearly 4 million smokers, but 70 percent of those want to quit, the survey found. Public health advocates were encouraged by a nearly four-point drop – from 22.2 percent to 18.3...