Get The Last, Say 4 Values For The Min, Max And Medium Value

My problems is, and this may be sloved in excel or with VBA. What i have is a number of results, Load and displacement takes at intervals in time. An example of data is below. I will know the min, medium and max numbers for load. What i would like to do is get the last, say 4 values for the min, max and medium value

for example, with the below data,
CloumnA CloumnB
1 (last value) 1
1 (last but one) 1.21
1 (2nd last) 1.2
.
.etc
.
210 (last value) 69.1
210 (last but one) 69
210 (2nd last) 68.9

how can i do this?

Date and time of resultLoadDisplacement
10/06/2006 12:05 10.2
10/06/2006 12:10 9010
10/06/2006 12:15 21050.........