git: latest changes grouped by day

lastDays.sh

#!/bin/bash
a=""
b=""
for i in $(seq 0 10)
do
    b=$(git diff --shortstat "@{ $i day ago }")
    if [[ "$b" != "$a" ]]; then
        echo $(date --date="$i days ago" +%F) $b
    fi
    a=$b
done

output

1 day ago 2 files changed, 144 insertions(+), 21 deletions(-)
3 day ago 2 files changed, 227 insertions(+), 73 deletions(-)

How this works? can i get results in days between? for example 1/1/2019 - 28/02/2019