$ git-stats --help
Usage: git-stats [options]

Options:
-s, --since <date> Optional start date.
-u, --until <date> Optional end date.
-n, --no-ansi Forces the tool not to use ANSI styles.
-l, --light Enables the light theme.
-a, --authors Shows a pie chart with the author related
contributions in the current repository.
-g, --global-activity Shows global activity calendar in the current
repository.
-d, --data <path> Sets a custom data store file.
-f, --first-day <day> Sets the first day of the week.
--record <data> Records a new commit. Don't use this unless you
are a mad scientist. If you are a developer, just
use this option as part of the module.
-r, --raw Outputs a dump of the raw JSON data.
-h, --help Displays this help.
-v, --version Displays version information.

Examples:
git-stats # Default behavior (stats in the last year)
git-stats -l # Light mode
git-stats -s '1 January 2012' # All the commits from 1 January 2012 to now
git-stats -s '1 January 2012' -u '31 December 2012' # All the commits from 2012

Your commit history is kept in ~/.git-stats by default. You can create ~/.git-stats-config.json to specify different defaults.

Documentation can be found at https://github.com/IonicaBizau/git-stats