I don't think that an overall statistic works very well for this.

I live in London and I probably do split my time very roughly 1/3 ish across the three modes as stated.

But that's because I'm doing different things.

The tube is used to go into town, meet up with urban living friends, go to museums, visit specialist high end shops.

The car is used to go to larger stores like the supermarket, big shopping centres, DIY stores, to go out of town, go to the golf range, visit friends and family.

Walking gets me to the corner shop, to local friends, to the park, the last mile on public transport.

It's very walkable/cyclable, I just don't spend my life in a 1-5 mile radius.