Не удается установить QGIS на Ubuntu 14.04 LTS

Я пытаюсь установить QGIS на Ubuntu 14.04 LTS. Я запустил следующее,

sudo add-apt-repository ppa:ubuntugis/ppa
sudo apt-get update
sudo apt-get install qgis

Но я получаю следующее сообщение:

The following packages have unmet dependencies:
  qgis : Depends: gdal-abi-2-1-0
    Depends: libgdal20 (>= 2.0.1) but it is not going to be installed
    Depends: libgeos-c1v5 (>= 3.4.2) but it is not going to be installed
    Depends: libqgis-analysis2.14.3 (>= 2.14.0) but it is not going to be installed
    Depends: libqgis-app2.14.3 (>= 2.14.0) but it is not going to be installed
    Depends: libqgis-core2.14.3 (>= 2.14.3) but it is not going to be installed
    Depends: libqgis-gui2.14.3 (>= 2.14.0) but it is not going to be installed
    Depends: libqgis-networkanalysis2.14.3 (>= 2.0.1) but it is not going to be installed
    Depends: python-qgis (= 2.14.3+dfsg-2~trusty1build1) but it is not going to be installed
    Depends: qgis-providers (= 2.14.3+dfsg-2~trusty1build1) but it is not going to be installed
    Depends: qgis-common (= 2.14.3+dfsg-2~trusty1build1) but 1:2.18.6+24xenial is to be installed
    Recommends: qgis-plugin-grass but it is not going to be installed
    Recommends: qgis-provider-grass but it is not going to be installed
    Recommends: qgis-plugin-globe but it is not going to be installed
E: Unable to correct problems, you have held broken packages.

Я все еще нуб Linux / Ubuntu и не знаю, как двигаться дальше.