Calculate the Hubble time

One can define a characteristic timescale for the expansion of the Universe (i.e. Hubble time $t_H$) using the Hubble parameter. Calculate the present-day Hubble time $t_{H0}$ in Gigayears. 1 year = $3.15{\times}10^7$seconds Hubble constant, $H_0 = 70$ $kms^{-1}/Mpc$.