  We present results from a survey of 12CO(J=1-0) spectra obtained for the
central regions of 68 nearby galaxies at an angular resolution of 16 arcseconds
using the Nobeyama Radio Observatory 45m telescope, aimed at characterizing the
properties of star forming molecular gas. Combined with similar resolution
observations in the literature, the compiled sample set of 166 galaxies span a
wide range of galactic properties. NGC 4380, which was previously undetected in
CO, was detected.
  This initial paper of a series will focus on the data and the gaseous
properties of the samples, and particularly on the degree of central
concentration of molecular gas in a range of morphological types, from early
(S0/Sa) to late (Sd/Sm) galaxies with and without bars. The degree of molecular
central concentration in the central kiloparsec, compared to the central
several kiloparsecs of galaxies, is found to vary smoothly with Hubble type, so
that early type galaxies show larger central concentration. The comparison of
barred and non-barred galaxies within early and late type galaxies suggest that
difference in Hubble type, representing the effect of bulges, is the more
important factor in concentrating gas into the central regions than bars.
