RE: Employee Count History
Sorry to ask, but US or Canadian Payroll?
I might consider looking for an activity that happens only once a year - T4 or W2 and searching for that record with the year restriction.
Do you have a lot of turn over - and then returning employees?
I might suggest looking at Termination Dates as well.
There are likely a number of different fields you could choose from.
But in all likelyhood, you would then dump the data for the past 10 years into Excel and do some sorting by calendar year - focus on Termination Dates or Last Paid dates.
Just some ideas.