Sacramento County Sheriff John McGinness says he will have to lay off 209 deputies if the county cuts $57 million from his budget as proposed. He paints a scary picture of a force sized for 1970 trying to serve 2009 population and crime levels. But how bad would that really be? Let's do the math. In 1970, the sheriff had 513 sworn deputies. Today, there are 1,498 deputies, almost three times the 1970s level. In that same time, the county's population doubled, going from 700,100 to 1,433,187. If the county lost 209 deputies, that would reduce the force to 1,289 smaller, certainly, but…