Wow, I've been on DT1 for 8 months in a row, what are the odds. Don't bother, I know they are perfectly calculable.
Only 107 eligible on the latest update so 7 miss out. My perception of time is pretty poor but at some stage in the not too distant past there were a lot more than 107 eligible. Your chances were a lot lower of a long DT1 streak then than they are currently.
Edit - Jan 25, pretty large drop off compared to now -
This month 140 users were eligible.
Even more bloated eligibility here -
This month 142 users were eligible.
And here -
This month 150 users were eligible.