Question on Linear Interpolation

Hello,
I have 2 columns with values and I need to find linear Interpolate values (Voltage) at the 4 different values @ 100nA, 1uA, 10uA, 100uA. Looking at my column B values there are no exact values matching these 4 but an approximation of closest vales to these 4 above. I have 16,000 files to go through and each one will vary so I can not treat every file as a static range. Not sure what I am doing wrong let alone starting to write the VB.
I used the forecast function in Excel but I get the value 14.9980. But looking at the columns it should be around 25V
= FORECAST(B134,A44:A131,B44:B131)
I put in column B134-->1E-07
I put in column B135-->1E-06
I put in column B136-->1E-05
I put in column B137-->1E-04
Column A (volts)
0.00E+00
3.50E-01
7.00E-01
1.05E+00
1.40E+00
1.75E+00
2.10E+00
2.45E+00
2.80E+00
3.15E+00
3.50E+00
3.85E+00
4.20E+00
4.55E+00
4.90E+00
5.25E+00
5.60E+00
5.95E+00
6.30E+00
6.65E+00
7.00E+00
7.35E+00
7.70E+00
8.05E+00
8.40E+00
8.75E+00
9.10E+00
9.45E+00
9.80E+00
1.02E+01
1.05E+01
1.09E+01
1.12E+01
1.16E+01
1.19E+01
1.23E+01
1.26E+01
1.30E+01
1.33E+01
1.37E+01
1.40E+01
1.44E+01
1.47E+01
1.51E+01
1.54E+01
1.58E+01
1.61E+01
1.65E+01
1.68E+01
1.72E+01
1.75E+01
1.79E+01
1.82E+01
1.86E+01
1.89E+01
1.93E+01
1.96E+01
2.00E+01
2.03E+01
2.07E+01
2.10E+01
2.14E+01
2.17E+01
2.21E+01
2.24E+01
2.28E+01
2.31E+01
2.35E+01
2.38E+01
2.42E+01
2.45E+01
2.49E+01
2.52E+01
2.56E+01
2.59E+01
2.63E+01
2.66E+01
2.70E+01
2.73E+01
2.77E+01
2.80E+01
2.84E+01
2.87E+01
2.91E+01
2.94E+01
2.98E+01
3.01E+01
3.05E+01
3.08E+01

Column B (Current)
5.00E-12
1.50E-11
1.50E-11
2.00E-11
3.50E-11
3.00E-11
1.50E-11
3.50E-11
7.50E-11
4.50E-11
5.00E-12
4.00E-11
5.00E-12
5.00E-12
1.00E-11
3.50E-11
5.00E-12
5.00E-11
5.50E-11
1.50E-11
2.50E-11
4.50E-11
5.00E-12
2.50E-11
1.00E-12
3.00E-11
1.50E-11
3.50E-11
2.00E-11
1.50E-11
2.50E-11
2.00E-11
2.00E-11
2.00E-11
1.50E-11
5.00E-12
4.00E-11
3.50E-11
1.00E-11
2.00E-11
5.00E-11
1.50E-11
3.00E-11
2.00E-11
2.00E-11
5.00E-11
5.00E-11
4.00E-11
7.00E-11
8.00E-11
1.15E-10
1.40E-10
1.95E-10
2.25E-10
2.85E-10
3.75E-10
4.75E-10
5.70E-10
7.10E-10
8.30E-10
1.13E-09
1.43E-09
1.89E-09
2.53E-09
3.58E-09
5.16E-09
7.54E-09
1.13E-08
1.70E-08
2.61E-08
3.98E-08
6.04E-08
9.22E-08
1.42E-07
2.26E-07
3.63E-07
6.20E-07
1.09E-06
2.08E-06
4.23E-06
8.29E-06
1.53E-05
2.84E-05
5.01E-05
8.80E-05
1.55E-04
2.74E-04
4.79E-04
1.00E-03

Any help is greatly appreciated.

Thanks,
Weenie