The "mode share" is probably commutes, but the accident stats probably include recreation, little kids, etc.
I've ridden the 2nd Ave trail in Seattle a several times, and actually live near it. It's popular. Also it turns an overly-wide avenue into a better street. Southbound through the CBD it's a downhill though...sometimes it's better to ride in a traffic lane, particularly when they have the light but due to car turns the bike lane is supposed to stop.
The bigger news for bicyclists in Seattle, which I rode Saturday...the 520 Bridge now has a bike lane. Now both bridges over the 18-mile-long Lake Washington have bike lanes. It was very busy. Now riding a "half lake north" loop is much easier -- about 36 miles from Belltown, vs. probably 45 for the quickest version using I-90. (Locals, try Juanita Drive from Kirkland to Kenmore...a bit hilly but a great route.)
https://www.google.com/maps/@47.5115.../data=!3m1!1e3