Any analysis of San Mateo County’s governmental spending habits in this decade has to come to one conclusion: The times have been very, very good for public employees. From 1999-00 through 2007-08, the per worker cost increase for the county was 7.7 percent on an annual basis. That’s more than double the rate of inflation during that time. In fact, in the past fiscal year, the county’s taxpayers were providing an all-time record average of $116,607 per employee, according to the county’s own figures. A significant portion of that number goes toward paying for retirement, health insurance and other benefits. The county’s ongoing gravy train shows some recent signs of slowing down as the Peninsula’s housing market and overall economy begin to throttle back. But the past nine years have been so generous for the county’s public employee unions and others in government in the halls of Redwood City and elsewhere that the bulk of the county’s spending requirements well into the future are locked in. That’s why county officials are wary of what may be coming down the line. If their tax haul is seriously impaired, all of those long-term commitments come home to roost without sufficient dollars to pay for them. Then the you-know-what will really hit the proverbial fan.