You won't find stats posted on interventional spots because the # of spots vary from year to year, and many spots are "unannounced" or created out of thin-air, so to speak because of how spots are funded.
Most positions are funded thru the federal government, and as such, are subject to the same disclosure rules that federally funded residency positions are. So if you get on Frieda, for example, you'll see a ballpark # of spots. But there are a number of spots funded thru grants, thru a private practice affiliated with a particular Cards fellowship program, or thru some other source, that aren't disclosed. These spots may be given to people whom a particular program wants to keep on for Intervention, or to other favorite people from elsewhere. They may have only one funded spot like this every couple of years or so, but you get the point.
Some things to consider about intervention/interventional spots:
1. Competition isn't what is used to be. The Cardiology job market is looking for more non-invasive/invasive Cardiologists than interventional ones. In the most unscientific method possible, look at the Cards job offers in the back of the NEJM, and compare how many offers for non-invasive/invasive there are compared to intervention. In private practice, at least, the demand for intervention is good, but not as brisk or robust as the others I've mentioned above. One caveat is academic interventional spots, where they can't get enough people. But as a result, getting interventional spots isn't as tough as it was before.
2. There are a mix of 1 and 2 year interventional spots. 2 year spots give you a better mix of coronary and peripheral intervention, although I've heard many places are now able to give you adequate training in both in 1 year. I don't know if this amount of time is adequate to do both, so may be worth asking others in the know.
3. Interventional Cardiology doesn't pay as well as it used to. I have a good friend who just finished fellowship at the Cleveland Clinic and was offered an interventional spot there which he subsequently turned down. He ended up joining a private group in Indy. His reasons for not doing intervention include a comparatively worse lifestyle in intervention, since most avg sized groups only have 4 or 5 interventionalists. But more than that (which matters once out of training) is that the $$$ in intervention is not what it used to be. 2-3 years ago, a 2v PTCA with stenting paid $2-3k. Today, it pays $700-800. With all the same overhead, malpractice, and other fixed costs, you do the math. Now if your passion is to balloon arteries open, then do what you need to do, but this is definitely food for thought.
4. What does pay well (soon to be the most, from what I understand) is imaging and nuclear -- TTE, TEE, DSE, AdThal, MUGAs, other nuclear studies, and sooner rather than later coronary CT/MRI. The latter will eventually supplant diagnostic catheterization. So what will eventually happen is that the only people getting cath'd are those for whom a percutaneous intervention is planned.
RTK gives some great advice for positioning yourself for fellowship.
Good luck!