Health Care Costs Continue to Rise By ADAM GELLER    NEW YORK (AP) -- Employers are facing continued double-digit increases in health care costs in 2005 and likely will require their workers to pay an even greater share of the bill, according to a new survey of more than 900 firms.    The survey, released Thursday by Mercer Human Resource Consulting, found that employers expect health care costs to rise 12.9 percent on average next year if they leave benefits unchanged...