Nice stats as usual, @paulag.

Some small hints to improve your query performances:

• avoid using SELECT * unless you really need all columns to be returned. You are downloading all comments' body, which is a huge amount data that turns to be useless for stats.

• CONVERT(datetime,'01/01/2017')
  better to use CONVERT(DATE,'2017-01-01') to avoid datetime locale issue with day and month.

• ( created >= CONVERT(datetime,'01/01/2017') AND created< CONVERT(datetime,'01/01/2018'))
YEAR(created) = 2017 will do exactly the same and is way faster.

• category in ('travel')
  better to use category = 'travel' to avoid the query optimizer to uselessly create an enumerator which contains only 1 element. Not a big deal, but best practice.

Hope that help ;)