Why Microsoft recommend to change email password every 72 days?

Suddenly I woke up to see a news about millions of emails got hacked recently.

So, I decide to change my password of my hotmail account.

In the Change Your Password page, I notice something that I can't find a pattern or why it relates to this specific number.

It is this.

What I have thought of so far:

• Month: 2 months 12 days NO
• Week: 10 weeks 2 days NO
• Day: 72 days NO
• Hour: 1728 hours NO
• Minute: 103,680 minutes NO
• Second: 6,220,800 seconds NO
• Year(365) / 2 = 182.5 days NO
• Year(365) / 2 = 91.25 days NO

So the question is why it has to be 72 days?