I didn't vote because I know these tests are not really reliable, and people don't use the same sound source, volume level and equipment. An ABX test with a silent track and without the start and end signaling from the test tone would be a much better idea, but still equipment and volume levels matter more IMHO.
To those who could only hear up to 14 or 15khz, it's mostly due to your headphones. Speakers generally give you a better results on the other hand, from what I have found. Ideally you'd need a "monitor" headphone (not speakers) with a linear (I mean linear, not just neutral) frequency response which is not available in any mainstream markets. Also, many people here are treble heads, which means the treble is accentuated so that's why so many of them can hear pass 18khz. In lab settings, the limit of human hearing is 20khz with many credible sources of scientific journal articles. Don't take this too seriously, is my advice. I'm sure some people would even claim to be able to hear 25khz or 30khz if given the options to pick. Note that I couldn't hear pass 14khz with IEMs (PL-30, M2, etc), but as you can from my signature I can hear higher frequencies with my current set up.
If you are worried about your hearing loss, and can afford it, see an audiologist for a formal test if that would give you some relief.