  Lifetimes of $2^+_1$ and $4^+_1$ states, as well as some negative-parity and
non-yrast states, in $^{188-200}$Hg were measured using $\gamma-\gamma$
electronic fast timing techniques with the LaBr$_3$(Ce) detector array of the
GRIFFIN spectrometer. The excited states were populated in the
$\epsilon/\beta^+$-decay of $J^\pi =7^+/2^-$ $^{188-200}$Tl produced at the
TRIUMF-ISAC facility. The deduced B(E2) values are compared to different
interacting boson model predictions. The precision achieved in this work over
previous ones allows for a meaningful comparison with the different theoretical
models of these transitional Hg isotopes, which confirms the onset of state
mixing in $^{190}$Hg.
