I have a straight table with column which has null in it. How would like to count how many null rfcode are missing which has a bond serial number and present per year? Would like to show this in KPI chart. This is just an example of how I have in my qsense app.
| Year | Receipt Date | Bondserial num | Device type | status | rfcode | Location | Power |
| 5 | 3/23/15 | WH5096 | chassis | Present | 17952 | PA | on |
| 6 | 9/23/14 | WHJ123 | chassis | Present | 17956 | PA | on |
| 2 | 2/7/18 | WH4357 | chassis | Present | | NY | on |
| 1 | 7/12/19 | WH9899 | filter-tray | Present | 179323 | NY | on |
| 4 | 10/20/16 | GXW1234 | filter-tray | Present | | OH | on |
| 3 | 10/9/17 | GWX97534 | chassis | Present | 1796788 | NY | on |
| 2 | 2/5/18 | RM12234 | chassis | Present | | OH | on |
| 7 | 9/30/13 | 343JT467 | chassis | Present | | NY | on |
| 7 | 12/16/13 | 3431258 | filter-tray | Present | | NY | on |
