3 ms·

In the USA, up through the 1970s(?) the correct amount was said to be 10%. Then it was 15% for a while. Now it's 20%. I'd like to see a historical analysis of h

by wrp 8y ago

In the USA, up through the 1970s(?) the correct amount was said to be 10%. Then it was 15% for a while. Now it's 20%. I'd like to see a historical analysis of how that developed.