Actually, depending on the weather, if you give the inside-panel door handle a good tug with one hand, the trunk lid ends up closing fully on its own. Works like this on many BMW models.
So just give it a good tug from the top position, It should close.
The weather does seem to affect the strength of the gas shocks. It's easier to pull down when the weather is cold, but even during the summer, the difference is negligible.