Actually more like: 65,000/104,000 = 62.5%, assuming someone is not in Masters quota.
Out of the 124k, 20k will be for masters. The remaining masters join the pool of lottery for 65k. So there are 65k spots available for 124k - 20k(=104k)
Just to add, out of 65,000, few visas are reserved for nationals of Chile(1400) and Singapore(5700) due to free trade agreements. These visas are called H1B1 and if unused, apparently they are added to visa cap for next year. Never heard about any increase in the cap (due to unused Chile/S'pore H1B1s) though.
Out of the 124k, 20k will be for masters. The remaining masters join the pool of lottery for 65k. So there are 65k spots available for 124k - 20k(=104k)