  We determine the most likely dark-matter fraction in the elliptical galaxy
quadruply lensing the quasar PG1115+080 based on analyses of the X-ray fluxes
of the individual images in 2000 and 2008. Between the two epochs, the A2 image
of PG1115+080 brightened relative to the other images by a factor of six in
X-rays. We argue that the A2 image had been highly demagnified in 2000 by
stellar microlensing in the intervening galaxy and has recently crossed a
caustic, thereby creating a new pair of micro-images and brightening in the
process. Over the same period, the A2 image has brightened by a factor of only
1.2 in the optical. The most likely ratio of smooth material (dark matter) to
clumpy material (stars) in the lensing galaxy to explain the observations is
~90% of the matter in a smooth dark-matter component and ~10% in stars.
