I would like to modify the way Excel ranks a range of values. An example
might be helpful:

value rank
4.6 1
4.7 2
4.9 3
5.1 4
5.2 5.5
5.2 5.5
5.3 7
5.4 8
5.5 9
5.6 10
5.8 11
6.1 12
6.2 13
6.3 14
6.5 15.5
6.5 15.5
6.8 17
7.2 18
7.7 19
8 20
8.1 21

As you can see, I would like the ranking to deal with identical values by
assigning them both the average rank of the values immediately adjacent to
them (see 5.2 as an example.). Is there a convenient way to do this?