Use 3 month and 5 month cross over as signal to enter or exit market.
Monitoring - once every month at last trading day of the month.
Buy - when 3M crosses above 5M
Sell - when 3M crosses below 5M
Since 2000, this system needs only 14 trades, avoids most of losses and captures most of the gains.
According to this system, if you are a long term investor, you should keep investing now until 3M crosses below 5M .