89% win rate this month shorting 0dte SPX 20 delta ICs at the open, sustainable?

Simply at market open I’ve been shorting 20 delta SPX iron condors with 10 wide wings. and holding to expiration unmanaged. Risking on average $700 to make $300 (it averages to be a $3.00 credit).

Don’t these usually expire worthless just 68% of the time. Can I keep doing this or is this month simply an anomaly?