  We visually analyzed the Transit Timing Variation (TTV) data of 5930 Kepler
Objects of Interest (KOIs) homogeneously. Using data from Rowe et al. 2014 and
Holczer et al. 2016, we investigated TTVs for KOIs in Kepler's Data Release 24
catalog. Using TTV plots, periodograms, and folded quadratic sinusoid fits, we
visually rated each KOI's TTV data in five categories. Our ratings emphasize
the hundreds of planets with TTVs that are weaker than the 200 or so that have
been studied in detail. Our findings are consistent with statistical methods
for identifying strong TTVs (Holczer et al. 2016), though we find some
additional systems worth investigation. Between about 3-50 days and 1.3-6 Earth
radii, the frequency of strong TTVs increases with period and radius. As
expected, strong TTVs are very common when period ratios are near a resonance,
but there is not a one-to-one correspondence. The observed planet-by-planet
frequency of strong TTVs is only somewhat lower in systems with 1-2 known
planets (7 +/- 1 percent) than in systems with 3+ known planets (11 +/- 2
percent). We attribute TTVs to known planets in multi-transiting systems, but
find about 30 cases where the perturbing planet is unknown. Our conclusions are
valuable as an ensemble for learning about planetary system architectures and
individually as stepping stones towards more detailed mass-radius constraints.
We also discuss Data Release 25 TTVs, about 100 KOIs with Transit Duration
and/or Depth Variations, and that the Transiting Exoplanet Survey Satellite
(TESS) will likely find roughly 10 planets with strong TTVs.
