I am trying to write a formula and I am looking for help:

I have thirteen columns of data, k-w, each of these columns is a range of
specific gravity:


K: <1.070
L: 1.070-1.075
M: 1.075-1.080
N: 1.080-1.085
O: 1.085-1.090
P: 1.090-1.095
Q: 1.095-1.100
R: 1.100-1.105
S: 1.105-1.110
T: 1.110-1.115
U: 1.115-1.120
V: 1.120-1.125
W: 1.125

Each row of data is a sample of objects, and the percentage by weight of the
objects is recorded in the appropriate column, ie the percentage of the total
weight that has a specific gravity that falls in that .005 range in gravity.
What I want to to is to write a formula that calculates what the highest
percentage of the sample falls within three consecutive columns, ie a range
of .015 in specific gravity. It has to be three consecutive columns. It
might be that for sample #1, the three consecutive columns with the highest
percentage by weight might be O,P,Q containing 77% of the objects by weight,
and for sample #2 S,T,U might contain 68% or whatever. Its not important
which columns it is for each row, just the total of those three. Its easy to
find the highest number, second highest, third highest but how can I find the
highest three consecutive? Suggestions?