  We present here the analysis of about 19,500 new star hours of low ecliptic
latitude observations (|b| < 20 deg) obtained by the Hubble Space Telescope's
FGS over a time span of more than nine years; which is an addition to the
12,000 star hours previously analyzed by Schlichting et al. (2009). Our search
for stellar occultations by small Kuiper belt objects (KBOs) yielded one new
candidate event corresponding to a body with a 530 +/-70m radius at a distance
of about 40AU. Using bootstrap simulations, we estimate a probability of approx
5%, that this event is due to random statistical fluctuations within the new
data set. Combining this new event with the single KBO occultation reported by
Schlichting et al. (2009) we arrive at the following results: 1) The ecliptic
latitudes of 6.6 deg and 14.4 deg of the two events are consistent with the
observed inclination distribution of larger, 100km-sized KBOs. 2) Assuming that
small, sub-km sized KBOs have the same ecliptic latitude distribution as their
larger counterparts, we find an ecliptic surface density of KBOs with radii
larger than 250m of N(r>250m) = 1.1^{+1.5}_{-0.7} x 10^7 deg^{-2}; if sub-km
sized KBOs have instead a uniform ecliptic latitude distribution for -20 deg <
b< 20 deg then N(r>250m) = 4.4^{+5.8}_{-2.8} x 10^6 deg^{-2}. This is the best
measurement of the surface density of sub-km sized KBOs to date. 3) Assuming
the KBO size distribution can be well described by a single power law given by
N(>r) \propto r^{1-q}, where N(>r) is the number of KBOs with radii greater
than r, and q is the power law index, we find q=3.8+/-0.2 for a KBO ecliptic
latitude distribution that follows the observed distribution for larger, 100-km
sized KBOs. 4) Regardless of the exact power law, our results suggest that
small KBOs are numerous enough to satisfy the required supply rate for the
Jupiter family comets. (Abridged)
