  We present a new constraint on the Hubble constant $H_0$ using the latest
measurements of the electromagnetic counterpart to the gravitational wave (GW)
event GW170817. We use the latest optical, X-ray and radio observations of the
afterglow up to $\sim 3.5$ years after the GW detection, and properly take into
account the impact of the host galaxy peculiar velocity. We find
$75.46^{+5.34}_{-5.39}$ km s$^{-1}$ Mpc$^{-1}$ (68\% Credible Interval), a
$\sim7\%$ precision measurement, which is a significant improvement compared to
the $14\%$ precision of the first standard siren measurement. Our result is
consistent within $1\sigma$ with the Cepheid-anchored Supernova and within $1.5
\sigma$ with the Cosmic Microwave Background measurements of the Hubble
constant. We also explore the impact of the various assumptions made when
fitting for the afterglow on the Hubble constant estimate.
