  All existing "positive" results on two neutrino double beta decay in
different nuclei were analyzed. Using procedure recommended by 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, $^{150}$Nd and $^{238}$U were obtained. Existing geochemical data
were analyzed and recommended values for half-lives of $^{128}$Te and
$^{130}$Te are proposed. We recommend to use these results as most precise and
reliable values for half-lives at this moment.
