This turnaround will take time, but it's coming.It can be tough to invest in healthcare stocks. They're at the mercy of government programs that set reimbursement rates, they face political pressure on drug pricing and premiums, and they get overshadowed in a booming stock market by high-flying sectors, such as technology.So far this year, the S&P 500 index is showing solid gains, up 12.5%. But the healthcare sector is a disappointment, down 1%.UnitedHealth Group (UNH 0.15%) is a leading company in the mana ...