According to your source " However, as Alberta is land-locked it is very
likely that all of Alberta’s imports of gas and gas liquids imports come from the U.S. and we have
therefore changed the U.S. share to 100%. "
Did you miss that part?
Do you know what land locked means?
Can you find Alberta on a map?
Nova Scotia could not sell nat.gas to Alberta even it wanted too.There are no pipelines pumping gas  in that direction ,it only comes east.
There is a reason for that.