TOKYO : Japan's service activity expanded for a second straight month in December, buoyed by solid demand and business expansion, a private-sector survey showed on Monday. The final au Jibun Bank Service purchasing managers' index (PMI) grew to 50.9 in December from 50.5 in November, according to the survey compiled by S&P Global Market Intelligence. It was lower than a flash reading of 51.4 but stayed above the 50.0 threshold separating expansion from contraction for a second straight month. "