By indicates when vaguely something happens. For a future date it means before:
The company vowed to ban all plastic containers by 2022.
Renewables can reduce CO2 emissions by 70% by 2050
It's a little weird to use if for a past date but I guess it work to. It would mean at some time before 2013.
I'm not 100% sure about this, but it could also mean around the year 2013.
After all, by is used in that sense for for spacial indications (the first definition is near or next to), so it could also apply for time indications.
He liked to sit by the tree.
It makes sense in your example.