If I understand you correctly, you would like to know the result of each gear's MPH Per 1,000 RPM.
In that case:
1st Gear = 5.5 MPH Per 1,000 RPM
2nd Gear = 8.6 MPH Per 1,000 RPM
3rd Gear = 12.0 MPH Per 1,000 RPM
4th Gear = 14.5 MPH Per 1,000 RPM
5th Gear = 17.0 MPH Per 1,000 RPM
6th Gear = 20.3 MPH Per 1,000 RPM
So your shift from to 1st to 2nd at 18 mph occurs when 1st gear is at 3,270 RPM, at which point 2nd gear would be at 2,090 RPM.
Hope that helps!