I think this is not a sign, but a common and usual condition for webhosts, to provide uptime guarantee. I haven't seen that anyone provided less than 99%. This is not an issue, this is not a factor of determination, this is just usual percentage for any hosting company, they could differ: Ahosting.biz - 99.5% for instance, some of them even claim to give 100%, but that is hardly possible. It means they have good uptime.