First find the number of cats that are females: 6 cats / 2 = <<6/2=3>>3 cats
Then find the total number of kittens born: 7 kittens/cat * 3 cats = <<7*3=21>>21 kittens
Then subtract the 9 kittens that were sold: 21 kittens - 9 kittens = <<21-9=12>>12 kittens
Then add the number of kittens to the number of adult cats to find the total number of cats: 12 kittens + 6 cats = <<12+6=18>>18 cats
Then divide the number of kittens by the total number of cats and multiply by 100% to find the percentage of cats that are kittens: 12 kittens / 18 cats * 100% = 66.666...%, which rounds up to 67%
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