Insights charts should display all the periods even if there are no data for them

As you can see here:

Screen_Shot_2019-04-10_at_18.23.48

We are missing some months that have no data (e.g. months after December 2017 and months from June 2014 to September 2014).

I think the charts should display empty bars for these periods.

/cc @markglenfletcher @godfat @meks