  We investigate evolution of clumpy galaxies with the Hubble Space Telescope
(HST) samples of ~17,000 photo-z and Lyman break galaxies at z~0-8. We detect
clumpy galaxies with off-center clumps in a self-consistent algorithm that is
well tested with previous study results, and measure the number fraction of
clumpy galaxies at the rest-frame UV, f_clumpy^UV. We identify an evolutionary
trend of f_clumpy^UV over z~0-8 for the first time: f_clumpy^UV increases from
z~8 to z~1-3 and subsequently decreases from z~1 to z~0, which follows the
trend of Madau-Lilly plot. A low average Sersic index of n~1 is found in the
underlining components of our clumpy galaxies at z~0-2, indicating that typical
clumpy galaxies have disk-like surface brightness profiles. Our f_clumpy^UV
values correlate with physical quantities related to star formation activities
for star-forming galaxies at z~0-7. We find that clump colors tend to be red at
a small galactocentric distance for massive galaxies with log(M_*/M_sun)>~11.
All of these results are consistent with a picture that a majority of clumps
form in the violent disk instability and migrate into the galactic centers.
