how long do your sprays last?

[pinksugarcandy]

To be precise, how long do the 10ml sprays last? When I received them, some were not full. Like maybe 90% full? I dont use the sprays everyday and each time I use I spray 3x but I noticed that they have gone down to 50% for those which were not full when I received them. Can evaporation happen? It scares me because it would mean I'll need to purchase again.

[NuTrix]

On the site, for each product, it tells you the approximate number of sprays per bottle, I believe under technical data...approx 80 sprays (usually a bit more) per 10ml bottle