"1 nine" tends to mean "90% availability" i.e. 37 days of downtime per year.
9% availability would be an uptime of ~33 days a year, I think at that point, we're pushing the semantics of "available" if the service is down the entire year except one month on average.
Since "N nines" for positive integers N denotes an uptime of 1 – 10^(–N), I think it's fair to analytically continue that formula, and say that 9% availability corresponds to 0.041 nines!
9% availability would be an uptime of ~33 days a year, I think at that point, we're pushing the semantics of "available" if the service is down the entire year except one month on average.