Retracements after strong surges a la since 3/23 per  1) &lt; 25% of initial gain '60 2)  75% of initial gain in '70 3) 62% in '79 4) close to none in '82 5) 38% in '84 6) 50% in '08 7) 23% in '09 8) 62% in '11 9) zero in '19  Place your bets $SPX $NDX $IWM