Multiple font weights in woff file?

Question

I uploaded a .ttc font file containing several weights to https://onlinefontconverter.com and got a .woff file. Does it contain all weights? How can I use them with CSS?

With the following declaration I can only use normal and bold, although there are many more weights in the original .ttc file.

@font-face {
    font-family: 'Avenir';
    src: url('avenir.woff') format('woff');
}