Oh he sounds vile.
There isn't a standard amount that people have sex (although twice a day is on the very high side for the vast mahority of people), but there is a very clear rule everyone should follow - if you don't have to have sex, don't have it.
Would you want to have sex with someone who didn't want to be doing it, but felt forced to by you?
He thinks that he is entitled to sex with you whenever he wants it. Even if you don't want it. Even if you don't enjoy it. He is using you as a stress relief (unbelievably offensive) and a receptical.
And his logic that you should be grateful he isn't an alcholic or gambler so you should be grateful and put up with sex you don't want is just vile. I assume you aren't a drunk or a gambler, so how does your husband thank you for that? Or does he just think you should be the grateful one? His arguement is nonsense.
No decent man would want their wife to have sex she doesn't want, just for his pleasure or stress relief. He would only want you to have sex you want. Sex is for both of your enjoyment, equally. If one doesn't want to do it, you don't do it. That's how decent and loving people operate.
He is coercing and bullying for in to sex you don't want. I can't imagine this is the only way he is selfish, disrespectful and uncaring. Someone so vile about their sex life is likely selfish and manipulative in other areas of life as well.