partitioning - /boot partition is always full

My /boot partition is always full after a few updates. I had always to delete the old version of the following files to regain some diskspace:

-rw-r--r--  1 root root  1271689 Nov  6 21:34 abi-3.19.0-xx-generic
-rw-r--r--  1 root root   177782 Nov  6 21:34 config-3.19.0-xx-generic
-rw-r--r--  1 root root 32608396 Nov 11 20:23 initrd.img-3.19.0-xx-generic
-rw-------  1 root root  3622220 Nov  6 21:34 System.map-3.19.0-xx-generic
-rw-------  1 root root  6623936 Nov  6 21:34 vmlinuz-3.19.0-xx-generic

Is this normal or is there something wrong with my installation?

Additional informations:

    # du -h /boot
    12K /boot/lost+found
    2.4M    /boot/grub/fonts
    2.1M    /boot/grub/i386-pc
    126K    /boot/grub/locale
    6.8M    /boot/grub
    93M /boot
    # df -h /boot
    Dateisystem    Größe Benutzt Verf. Verw% Eingehängt auf
    /dev/sdb1       236M     95M  130M   43% /boot

There is a solution for you in this question, or this even older question

The basic suggestion of both is to use Ubuntu Tweak or Synaptic package manager to help with limiting the number of old kernels in the system.