  All existing positive results on two neutrino double beta decay in different
nuclei were analyzed. Using the procedure recommended by the Particle Data
Group, weighted average values for half-lives of $^{48}$Ca, $^{76}$Ge,
$^{82}$Se, $^{96}$Zr, $^{100}$Mo, $^{100}$Mo - $^{100}$Ru ($0^+_1$),
$^{116}$Cd, $^{130}$Te, $^{136}$Xe, $^{150}$Nd, $^{150}$Nd - $^{150}$Sm
($0^+_1$) and $^{238}$U were obtained. Existing geochemical data were analyzed
and recommended values for half-lives of $^{128}$Te, and $^{130}$Ba are
proposed. Given the measured half-life values, nuclear matrix elements were
calculated using latest (more reliable and precise) values for phase space
factor. Finally, previous results (PRC 81 (2010) 035501) were up-dated and
results for $^{136}$Xe were added.
