i have a very similliar question, but you were faster
I think his voice was best in the 80ies and 90ies.
Maybe I'm wrong but for me it seems to be that he changed his way of singing to a ,IMO, worse way: I think he sings in a more nasal way and squeezes the voclas more then in the past("The Distance": ther#s a traaaaaaaaaaaaaaaaaaaaaaaaaaiiiiiiiiiiiiiiiiiiiiii iiiiiiiiin out in the distance; Destinaaaaaaaaaaaaaaaaaaaaaaaaaaaaaation still unknown). Did somebody else recognize that?
I think Jons voice had it's best days already;but its still good enough.