What happened to sonic booms?

As a child growing up in Siskiyou County during the '80s, I remember hearing sonic booms frequently. We're talking on a weekly basis here. I heard them all the freakin' time. And after conferring with some Siskiyou natives around my age, they also recall hearing them with a similar frequency through that time period. However, something has changed...

Sometime in the early-mid '90s, I stopped hearing sonic booms with any regularity. In fact, I can say with some significant level of certainty that I haven't heard a sonic boom in 10 years or more. Not in Siskiyou County, not anywhere. I ran this by Brenda, and she says the same. So, what happened to them?

Thinking on this some more, I wonder why the heck I heard so many sonic booms back in the day. Siskiyou County was nowhere near any military bases, so I don't even know what super-sonic jets would be doing in the area. Maybe I just heard the sonic booms more often because I was outside more often as a child. But then I have trouble believing that in all the time since the initial decline, I've somehow managed to hear no sonic booms, despite living much nearer military bases for the past seven years. Hrmmm, perhaps this is all part of some government conspiracy...

Anyway, I'd like to get to the bottom of this. Initial internet searches have turned up very little information. Do any of you out there reading have anything to say on this? Have you noticed the same drastic downturn in sonic booms that I have? Let me know in a comment...