A study in Toronto, Canada found that having 10 more street trees on a city block, on average, improves health perception in ways comparable to an increase in annual personal income of $10,000 and moving to a neighborhood with $10,000 higher median income or being 7 years younger.
Kardan, Omid, Peter Gozdyra, Bratislav Misic, Faisal Moola, Lyle J. Palmer, Tomáš Paus, and Marc G. Berman. (2015). Neighborhood greenspace and health in a large urban center. Scientific Reports, 5.