Below are my build instructions for GnuPG 2.2.1, released on September 19th, 2017. These instructions are built for a Ubuntu 16.04 LTS.
If you prefer, you may use the below install script to install GnuPG 2.2.1 by running the following commands:
curl -OL "https://gist.github.com/romen/b7bac24d679d91acabb27bfcdabbee01/raw/b93b7b00910db67c2c3332606792679802abbb32/install-gnupg22.sh" && bash ./install-gnupg22.sh