Luke:
The table you want could have been produced 4 days ago if you would just have used the Summary Statistics tool. The "category" field would be the input to the case_field parameter. A frequency field will automatically be generated that gives the counts you want, so you don't really need a summary to get the output you want, but the tool requires at least one summary parameter input. Since any field can be used for the summary, just use the "category" field and get its Count to duplicate the values in the Frequency field.
The output of the Summary Statistics tool will be a table that can be joined back to your original data for SQL selections and/or field calculations, or any of other uses that have been discussed so far. Do not tell me that the tool cannot do what you want, because it definitely can. As an example, here is the Summary Statistics tool output counting the codes that define my recorded map feature class categories:
OBJECTID * | RECORDERS_TYPE | FREQUENCY | COUNT_RECORDERS_TYPE |
1 | MB | 11977 | 11977 |
2 | PM | 12159 | 12159 |
3 | RS | 4141 | 4141 |
4 | SB | 96 | 96 |
5 | SD | 134 | 134 |