Amount of mortgage "responsible for" for property with joint tenancy with partner

[Jane Mipsey]

Hello, I had a tax question -- my partner and I bought a primary residence last year -- we are not married therefore, are filing taxes separately.  In filing taxes, there is a how much mortage are you "responsible for" question, in relation to how much mortgage interest I can deduct on my tax return.  My partner is unemployed and I have been making 100% of the payments.  Is this "responsible for" amount 50% of the mortgage principal or should I put all 100%?  Thank you!