If you are making your own website registration form, then on the of chance you want an age selection box then don't spend hours manually typing it in, just a 3 lines of PHP and it will automatically do it for you. Very simple!
Below is the tiny bit of code that will automatically make a dropdown box for your site. Basically it starts at 1 and goes to 100. If you want to change the numbers then edit the $i = 1 value, which is the number it starts on, then edit the $i < 101 value, which is the number it goes upto plus one, so 54 would go upto 53.