Indianapolis 500 - A Uniquely American Tradition

I grew up listening to the Indy 500 race coverage on the radio hearing names like Johnnie Parsons, Bill Vukovich, Roger Ward, A.J. Foyt, Parnelli Jones, and of course, the Unser brothers.
I well remember the 'British Invasion' of the early 60's when names like Jimmy Clark and Graham Hill first became associated with the 500, and when the rear-engine Lotus created such a stir as the design started replacing the famed Offy-powered roadsters with names like Kurtis-Kraft and Watson.
Today I'm watching the television coverage and see only 15 of the 33 drivers are from the United States. And on top of that NBC has a Brit lead announcer doing race coverage.
What's happened to all the talented American drivers? Are they all going to NASCAR?
OC you forgot to mention that the car are either [powered by Honda engines (Japan) or by"chevy" engines built in England. Any similarity to American cars or engines is a joke.