Better plotting of single year of data

[jdebacker]

This PR updates the plotting in demographics.py to only plot a single year if start_year and end_year are the same.

[codecov-commenter]

Codecov Report

Attention: Patch coverage is 35.29412% with 11 lines in your changes missing coverage. Please review.

Project coverage is 71.29%. Comparing base (d76096f) to head (410af1c).

Additional details and impacted files

[](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952?src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) ```diff @@ Coverage Diff @@ ## master #952 +/- ## ========================================== - Coverage 71.40% 71.29% -0.12% ========================================== Files 20 20 Lines 4949 4954 +5 ========================================== - Hits 3534 3532 -2 - Misses 1415 1422 +7 ``` | [Flag](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952/flags?src=pr&el=flags&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) | Coverage Δ | | |---|---|---| | [unittests](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952/flags?src=pr&el=flag&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) | `71.29% <35.29%> (-0.12%)` | :arrow_down: | Flags with carried forward coverage won't be shown. [Click here](https://docs.codecov.io/docs/carryforward-flags?utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels#carryforward-flags-in-the-pull-request-comment) to find out more. | [Files](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952?dropdown=coverage&src=pr&el=tree&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels) | Coverage Δ | | |---|---|---| | [ogcore/\_\_init\_\_.py](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952?src=pr&el=tree&filepath=ogcore%2F__init__.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels#diff-b2djb3JlL19faW5pdF9fLnB5) | `100.00% <100.00%> (ø)` | | | [ogcore/parameter\_plots.py](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952?src=pr&el=tree&filepath=ogcore%2Fparameter_plots.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels#diff-b2djb3JlL3BhcmFtZXRlcl9wbG90cy5weQ==) | `82.28% <42.85%> (-0.14%)` | :arrow_down: | | [ogcore/demographics.py](https://app.codecov.io/gh/PSLmodels/OG-Core/pull/952?src=pr&el=tree&filepath=ogcore%2Fdemographics.py&utm_medium=referral&utm_source=github&utm_content=comment&utm_campaign=pr+comments&utm_term=PSLmodels#diff-b2djb3JlL2RlbW9ncmFwaGljcy5weQ==) | `55.68% <22.22%> (-0.91%)` | :arrow_down: |

[rickecon]

@jdebacker. This is great. Merging.