The cost of health care for a family of four has increased 7.3 percent in 2011, to $19,393, according to the Milliman Medical Index.

This is the lowest annual rate of increase in more than a decade, Milliman said. However, the typical family of four is paying $1,319 more this year for a preferred provider plan, which is the highest dollar amount increase in the history of the index.

“In 2002, American families had health care costs of $9,235, and those costs have now doubled in fewer than nine years,” said Lorraine Mayne, Milliman principal and consulting actuary. “As costs continue to grow and even as the cost trend decelerates  the total cost of care for American families constitutes a larger and larger portion of the household budget.”

Of the $1,319 cost increase, employers paid $641 while employees bore the remainder  $403 in payroll contributions and $275 in additional cost sharing.

The Milliman Medical Index also examined 14 geographical areas, and found six of the 14 cities studied exceeded $20,000 in total health coverage costs for a family of four. Phoenix had the cheapest coverage with an annual cost of about $17,300 for a family of four. Atlanta and Seattle also had less than $19,000 in total costs for a family of four.   Denver Colorado averaged $19,199 for a family of four.