https://www.cityandstateny.com/articles/policy/infrastructur...
The best public transport model is the one in London.
I did a quick and dirty check on Google for "new york state population" [0] and " "new york city population" [1] and the percentage I get is 43%.
[0] https://imgur.com/a/2zkmdjm
[1] https://imgur.com/a/904hwM2
EDIT: As did a few others, I read "<0.5" as "<0.5%".
I'm assuming you're using the "worthless" adjective only for the streetcars - I use the NYC Ferry regularly (a stop opened near my apt last year) and it's way better than the subway. I have to walk a bit further on the other side, but it's still way more comfortable.
However, it is a valuable augment to the surface system. The point is that it helps "connect the dots" (providing more options for people to get from A to B) - hence making the system more effective as a whole.
They don't compare remotely favorably to the subway along any axis except start-up cost (it's cheaper to buy a boat and build some piers than to build a subway tunnel).
Which is, well, hugely significant when you think about it.
Some people tried to make the math work for the L shutdown and even if you had a line of ferries just following each other as close as safely possible it wouldn’t be nearly enough. Subways are incredibly efficient at moving large numbers of people.
But I guess those discussions will need to happen elsewhere.
Worthless? The ferries are one of the few unequivocally positive things to have happened to the city in recent decades.
Hence why the NYC mayor is so intent on funding worthless streetcars and ferries; they let him get out from under the thumb of the state.