Issue 302 derived curve

[TatianaBurek]

• Describe testing already performed for these changes:

• created and run testing script test_agg_ratio.py

• tested with GUI on dakota

• Recommend testing for the reviewer(s) to perform, including the location of input datasets, and any additional instructions:

• run testing script test_agg_ratio.py

• Do these changes include sufficient documentation updates, ensuring that no errors or warnings exist in the build of the documentation? [No]

• Do these changes include sufficient testing updates? [Yes]

• Will this PR result in changes to the test suite? [No]
  
  If yes, describe the new output and/or changes to the existing output:
  

• Please complete this pull request review by [Fill in date].
  

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[bikegeek]

tests pass