One way to demonstrate this is to remember that the gap between domestic saving and investment must be equal to the current-account balance, which is probably measured more accurately.
So following on from the piece I wrote on the old Mind the Gap blog (RIP) about saving money on fares, I've come across another way for rail passengers to save a few quid.
Also, consumers are no longer saving less and borrowing more on credit card, home equity and other loans to bridge the gap between income and desired spending growth.