1,000,000th safe image on about 1.5 million. This would indicate the site is about 67% safe. Not bad. Now I’m curious about the breakdown. I’ll have to run some numbers sometime when I’m not staying up to 6am and in desperate need to just go sleep.

Now, we have a “1000000th Safe Image” tag, it’s-
 
Siren goes off
 
Derpy Hooves : What’s going on?  
Twilight Sparkle : Something stupid. I’m sure.
 
Alarm stops, a curtain opens up to show a real band playing music, song plays, and Trixie comes out
 
Trixie : Yippie! kisses two random anons. Takes this image and rubs it all over herself Whoo-ha! Whoo-ha!  
Twilight Sparkle : See? I told you.  
Spike : What’s wrong with Trixie?  
Trixie : runs over to Twilight and Spike Nothing, lad! Do you know what this is?!  
Twilight Sparkle : A wallpaper edit of me and Pinkie in a human world’s Canterlot Wedding?
 
Trixie : No, this is my one millionth Safe image posted in Derpi! Every pony’s goal in a site is to make a million Safe images, and now I got mine! Congratulations, OP! You uploaded Derpibooru’s millionth safe image!
 
OP : Ha, great! Uhh, what do I win?  
Trixie : Nothing! Now get out!  
OP : Uhh, what?  
Trixie : pushes everyone out the door Get out! Everypony get out, you’re spoiling my moment!

@RushCars24  
Or perhaps it’s her brother’s wedding. ;)

One million safe images, and I love these dresses!!!!

One million Safe images!
 
Twilight seems that she have been starstruck for seeing Flash Sentry or being kissed by Pinkie Pie!

One million safe images!

Safe picture # 1,000,000!!
 

Congratulations OP, you uploaded Derpibooru’s millionth safe image.