Roughly-estimate total contributions to a Git repository (adds + deletes). Arguably overstates the impact of a move (you get twice the file size in those cases).

contrib.sh

#!/bin/sh
git log --numstat | awk '/^Author: /{author=$0} /^[0-9]+\t[0-9]+/{n = $1 + $2; d[author] += n; t += n} END { for(a in d) { printf("%6d  %6.3f%%  %s\n", d[a], d[a] * 100 / t, a)}}' | sort -rn

# written less illegibly, it is:
#
# git log --numstat | \
#   awk '
#     /^Author: /{author=$0}
#     /^[0-9]+\t[0-9]+/{n = $1 + $2; d[author] += n; t += n}
#     END { for(a in d) { printf("%6d  %6.3f%%  %s\n", d[a], d[a] * 100 / t, a)}}
#   ' | sort -rn

Cool! If you rename that script git-contrib, you can then execute it by typing git contrib, which is kinda cooler…

Looks like you need to ignore case for the author. Authors with inconsistent case sign-off are shown more than once in the output.