Looking at honda accord, cr-v, element and TSX sales for March 2005, the number is 54,786 so let's assume 50K. Some of the accords are V6, so assuming half the accords are 4 cylinders... that bring the number down to 35K cars...
So, from 2002-2006, there should be around 2 million k24a engines on the road... Not bad at all.
Here's a screenshot