Clearest way to say "penultimate?"

Question

I have a series of paired bar charts that show the most recent administration of a survey immediately adjacent to the next most recent administration for a given client. The two time points are two different colors. In the legend, I want a clear way to express the concept of the latest administration as distinct from the time before that, so it is clearly understood what is being compared.

Options that have occurred to me:

• Most recent vs. next most recent
• Most recent vs. penultimate
• Most recent vs. previous-to-most-recent

Each of these is awkward to read and say, and in the case of "penultimate" the word is possibly unknown to audience members. Are there any other suggestions out there that I've overlooked?

Answer 1

Use “current” and “previous.”

The most-recent numbers you have are the current numbers. The ones before that are the previous numbers. If you have to go further back than that, use dates: January 15th numbers, January 1st numbers.

If you were talking about episodes of a TV show, the one you watched last night is the current episode. The one you watched last week is the previous episode. The one before that is the January 27th episode.

Answer 2

N^th and N-1^th for the relevant terms of the sequence.

nth in Cambride dictionary 

used to ​describe the most ​recent in a ​long ​series of things, when you do not ​know how many there are: I ​glanced at my ​watch for the nth ​time that ​morning.

Answer 3

Were I in the audience I would clearly understand "previous administration". The audience knows the subject of your presentation. If your audience is being obtuse state the date of the previous administration, i.e., "1997 administration".