Is there any substitute for the vlookup function when the table
lookup_values are numbers but not in a continuing descending order?

For example:
A1 B1
1 5.5
8 5.6
14 5.7
19 5.8

Works: look for the number 1 in the table A1:B1 and return the second
column, if not zero = the result is 5.5

Does not work: look for the number 2 in the table A1:B1 and return the
second column, if not zero =the result is 5.5 as well instead of zero.

I know I can manually fill the numbers between 1 and 8, but if it is a
very big table, I don't want to spend too much time on that.

Thanks.