When checking the discovery date facets, there are instances where not all years are correctly added.
For example, when the "oldest" and "newest" year are 2007 and 2017 respectively, the facet only retrieves 10 results (2017-2007=10 being the difference in year).
This, however, is not correct, as exactly 10 years apart in dates actually results in the following 11 year-values (2007 being the first one, 2017 being nr 11)
This will result in 2017 not being added properly when faceting on dates.
A quick fix has been added that takes into account that both start and endyear need to be included in this query.
(And, because more than 10 results are returned, these values will be grouped)