Q1
What does "correctly predicted nine of the last five American recessions." mean?
If it said "correctly predicted three (or four or five) of the last five" I would understand.
When 5 things happens, you can not predict more than 5....

Q2
What does "His profession would kill for such accuracy." mean?


Context>>>>>>>>>>
In 1966, four years before securing the Nobel Prize for economics, Paul Samuelson quipped that declines in U.S. stock prices had correctly predicted nine of the last five American recessions. His profession would kill for such accuracy.

With recession talk returning to haunt financial markets and the corridors of central banks, a review of the past suggests that those who are paid to call turning points in economic growth have a dismal record. Unlike the stock market, they’re more likely to miss recessions than to predict ones that never occur. The lowlight, of course, was the widespread failure to forecast America’s Great Recession, which began in December 2007—nine months before Lehman Brothers filed for bankruptcy.