Growing number of packages not being upgraded

[Frank McCormick <debianlist@videotron.ca>]

Each upgrade it seems there are a growing number of packages
being held back by apt-get.
It started off as a few packages a few weeks ago and now is
23:


Calculating upgrade... Done
The following packages have been kept back:
  cups-filters gir1.2-pango-1.0 libcdr-0.0-0 libdee-1.0-4 libgegl-0.2-0 
libharfbuzz-dev
  libharfbuzz-icu0 libjavascriptcoregtk-1.0-0 libjavascriptcoregtk-3.0-0
  libmateweather-common libmatewnck-common libmspub-0.0-0 
libpango-1.0-0 libpango1.0-0
  libpango1.0-dev libpangocairo-1.0-0 libpangoft2-1.0-0 
libpangoxft-1.0-0 libtiff4
  libtiff4-dev libtiffxx0c2 libwebkitgtk-1.0-0 libwebkitgtk-3.0-0
0 upgraded, 0 newly installed, 0 to remove and 23 not upgraded.
root@frank-debian:/home/frank#


How can I find out what is holding these packages ?

Thanks