Hi all, I have a simple example input
| Year | Country | Amount |
| 2015 | US | 90 |
| 2015 | Canada | 95 |
| 2016 | US | 100 |
| 2016 | Canada | 105 |
| 2017 | US | 110 |
I want to get the prior year amount as another column, when I do a join I can get
| Year | Country | Amount | PY Amount |
| 2015 | US | 90 | 0 |
| 2015 | Canada | 95 | 0 |
| 2016 | US | 100 | 90 |
| 2016 | Canada | 105 | 95 |
| 2017 | US | 110 | 100 |
But I want to get
| Year | Country | Amount | PY Amount |
| 2015 | US | 90 | 0 |
| 2015 | Canada | 95 | 0 |
| 2016 | US | 100 | 90 |
| 2016 | Canada | 105 | 95 |
| 2017 | US | 110 | 100 |
| 2017 | Canada | 0 | 105 |
The last line 2017 - Canada isn't showing up if I do a join. Can someone help me with this?